Imagine this: A long day at work is behind you. The children are in bed, the garden is quiet, and you're looking forward to the one thing you bought the hot tub for – half an hour just for yourself, in warm water, under the starry sky.
They lift the cover. And then this: The water is milky and cloudy. It smells strange. The walls feel slippery. Instead of relaxation, there's frustration. Instead of wellness, there's work.
This moment – it's avoidable.
Because good water care isn't rocket science. It's not an endless checklist of chemicals, measurements, and complicated formulas either. Water care is simply the foundation for ensuring your hot tub does exactly what you bought it for: giving you a little escape every day without you having to worry about it.
And yes, there's no way around disinfectants. The good news: you have a choice. And you don't have to choose between "chemical" and "natural" – but between tried and tested, convenient, or alternative .
In this guide I will show you:
- Why chlorine has an undeservedly bad reputation – and why it's the best choice for most hot tub owners
- What three alternatives exist (salt electrolysis, active oxygen, bromine) – and for whom they really make sense.
- How to keep your water crystal clear with a simple routine, without having to stand by the hot tub every evening.
- What you need to know about pH, alkalinity and filter cleaning – in easy-to-understand German, not in chemistry lab jargon.
The goal is simple: they should be able to open the cover in the evening, get into the water – and think of nothing more than: "That's exactly why I got this."
➡️ Book a free hot tub consultation
Let's get started.
1. A comparison of the four disinfection methods
Before we go into detail: All four methods work. Each has its merits. The question isn't "What's right?", but "What suits me, my hot tub, and my daily routine?"
Let's start with the method that is most misunderstood – and yet has been the number 1 worldwide for over 100 years.
2. Method 1: Chlorine – The tried and tested classic
Why chlorine is better than its reputation
Chlorine has an image problem.
When most people hear "chlorine," they think of: the smell of swimming pools. Burning eyes after a day at the pool as a child. Dry skin. "Chemicals." Something they'd rather avoid if there were an alternative.
But here's the truth you've probably never heard before:
The typical "chlorine smell" has nothing to do with chlorine.
It is formed by chloramines – compounds of chlorine and organic substances such as sweat, skin flakes, cosmetics, or urine. Chloramines are formed when there is too little free chlorine in the water, not when there is too much.
Properly dosed, fresh chlorine has hardly any smell. If your hot tub smells of "chlorine," that's actually a cry for help: there's too little chlorine, not too much.
The same applies to skin irritations and burning eyes.
The cause is almost always an incorrect pH level – not the chlorine itself. If the pH level is within the ideal range (7.2–7.6), most people tolerate chlorine without any problems.
And then there's the elephant in the room: "Chlorine is toxic, isn't it?"
Yes, in high concentrations. But at the dosage you use in your hot tub (1.0–1.5 mg/l), chlorine is so harmless that it has been used worldwide for drinking water treatment for over 100 years. It saves lives every day because it reliably kills pathogens.
This isn't "evil chemistry." This is science that works.
The benefits of chlorine – honest and without embellishment
Chlorine is the most reliable disinfection method available.
✅ Works quickly and reliably – kills bacteria, viruses, fungi and algae within minutes
✅ Works even at high temperatures – perfect for hot tubs at 38–40°C
✅ Inexpensive to purchase – no expensive equipment, no complicated systems
✅ Flexible dosage – whether granules after every bath or tablets for basic care
✅ Wide selection – available everywhere, easy to store
✅ Tried and tested for over 100 years – millions of people worldwide use chlorine daily
This means specifically for you:
If you spontaneously decide to jump into the hot tub after a long day, you can rest assured that the water is clean. No guesswork. No "I hope there's enough water left." It simply works.
You don't need to buy expensive equipment, perform complicated measurements, or worry about special storage. You buy a product, dose it – that's it.
And if you use your hot tub intensively (family, friends, several times a week), then chlorine is the method that won't give out even under heavy use.
The disadvantages of chlorine – because honesty matters
No method is perfect. Not even chlorine.
❌ Regular replenishment required – daily to weekly depending on usage
❌ Can cause irritation if overdosed or at the wrong pH level – therefore, regular measurements are important.
❌ Chloramines can form if there is too little free chlorine; therefore, shock chlorination is recommended once a week.
❌ Not suitable for everyone – people with a chlorine allergy or very sensitive skin should consider alternatives.
But:
Most of these "disadvantages" can be avoided with a simple routine:
- Measure and adjust pH value once a week
- Add chlorine granules after each bath (or every few days).
- Shock chlorination once a week to prevent chloramines
That's 10 minutes per week. Not per day. Per week.
If you don't want to or can't spare those 10 minutes, then a salt electrolysis system might be the better choice (more on that in a moment). But if you're willing to invest a minimum of attention, chlorine offers the most reliable water treatment available.
For whom is chlorine ideal?
Chlorine is the right choice for you if:
- You want a proven, reliable method that simply works.
- You use your hot tub frequently (several times a week, family, guests)
- They do not want to make a large initial investment
- They are willing to invest 10 minutes per week in water care
- They appreciate clear-cut solutions : measure, dose, done.
In short: For the vast majority of hot tub owners, chlorine is the best choice. Not because it's "more natural" or "gentler" – but because it has proven its effectiveness for over 100 years.
How do you use chlorine correctly?
There are two common forms:
1. Chlorine granules (fast-dissolving)
- Dissolves within minutes
- Ideal for dosing directly after each bath
- Flexible: You add exactly the amount you need.
- Application: 5 g per m³ of water after each bath, run filtration for 10 minutes, then check with test strips.
2. Chlorine tablets (slow-dissolving, multifunctional)
- They dissolve slowly over several days.
- Ideal for consistent basic nutrition
- Often contain additional algaecides
- Application: 1 tablet (20 g) per m³ every 7 days in the filter box or dosing float.
Guideline: The free chlorine level should always be between 1.0 and 1.5 mg/l. Measure once a week using test strips.
Important: Chlorine works optimally only when the pH value is between 7.2 and 7.6. Always check the pH value before adding chlorine.
The conclusion regarding chlorine:
Chlorine is not a "chemical weapon". It is a proven tool that has provided clean water to billions of people worldwide for over 100 years.
If you're buying your hot tub to relax in the evening after work – and not to deal with complicated maintenance systems – then chlorine is your best ally.
Reliable. Affordable. Tried and tested. Simple.
And if you are still looking for an alternative – for whatever reason – then let's take a look at the three other methods.
3. Method 2: Salt electrolysis – convenience through automation
Imagine your hot tub disinfecting itself. No weekly dosing. No calculating. No "Did I add enough?" or "Do I need to add more?".
That's exactly what salt electrolysis promises.
And before anyone objects: "But I want to get away from chlorine!" – here's the most important information first:
Salt electrolysis is not chlorine-free. It produces chlorine automatically.
The difference to traditional chlorine: you no longer add granules or tablets. Instead, an electrolysis cell does the work for you.
How does salt electrolysis work?
The principle is simple:
- They add commercially available salt to the water (approx. 3–4 kg per 1,000 liters, once only).
- An electrolysis cell is installed in the water circuit.
- When the water flows through the cell, the salt is converted into chlorine through electrolysis.
- The chlorine disinfects the water.
- Once the job is done, the chlorine turns back into salt.
A closed loop.
They don't taste the salt (the concentration is significantly lower than in the sea). They don't smell chlorine (because no chloramines are formed by adding granules). They do: nothing.
The system does the work.
The advantages of salt electrolysis – when comfort counts
✅ Automatic chlorine production – no more manual dosing required
✅ Soft, pleasant skin feel – many users describe the water as “silky”
✅ No chlorine odor – as no chloramines are produced by adding granules
✅ Consistent disinfection – the system continuously produces the correct amount
✅ No need to store chlorine products – no granules, no tablets, no need to buy more.
✅ More economical in the long run – salt is significantly cheaper than chlorine products
This means specifically for you:
They come home. They get into the hot tub. They get out again. Done.
No test strips. No granules. No thoughts of "Do I need to do anything else?".
The system runs in the background, producing exactly the amount of chlorine needed – and you simply enjoy.
If you are someone who uses their hot tub daily or several times a week and doesn't want to deal with water care, salt electrolysis is the convenience you are looking for.
The disadvantages of salt electrolysis – because honesty counts here too.
Sounds perfect? Almost. But there are a few things you should know beforehand:
❌ High initial investment – A salt electrolysis system costs between 800 and 2,000 euros, depending on the model and size.
❌ Electrolysis cell maintenance – The cell must be cleaned regularly (every 3–6 months), otherwise limescale will build up and performance will decrease.
❌ Cell lifespan is limited – the cell must be replaced after 3–5 years (cost: 300–600 euros)
❌ Only works at the correct pH level – If the pH level is too high, the cell produces chlorine less effectively.
❌ Not suitable for all hot tubs – Some manufacturers do not recommend salt electrolysis (e.g., for certain materials)
❌ Ultimately, it also produces chlorine – anyone who wants to avoid chlorine altogether is in the wrong place here.
The most important point:
Salt electrolysis is an investment . It will cost you significantly more than traditional chlorine in the first year. However, it pays for itself over the years – if you use the hot tub intensively.
Calculation example:
- Classic chlorine: approx. 200–300 euros per year (with regular use)
- Salt electrolysis: approx. €1,200 purchase price + €50 salt per year + €400 cell replacement every 4 years
Break-even after approximately 3-4 years.
If you plan to use your hot tub for at least 5 years and value comfort, the investment is worthwhile.
For whom is salt electrolysis ideal?
Salt electrolysis is the right choice for you if:
- Use your hot tub regularly (at least 3-4 times per week)
- They prioritize comfort over cost – and are willing to invest 1,000–2,000 euros.
- You don't have the time or inclination to deal with water care on a weekly basis.
- They appreciate the soft skin feel of salt water
- If you plan to use your hot tub for the long term (5+ years)
In short: If you can afford the purchase costs and love the idea of not having to worry about anything anymore – then salt electrolysis is the system for you.
How do you use salt electrolysis correctly?
1. Installation
The electrolysis cell is installed in the water circuit between the filter and the hot tub. Installation is usually carried out by a specialist company (or by you if you are skilled in DIY).
2. Adding salt
After installation, add approximately 3–4 kg of salt per 1,000 liters of water. Use ordinary table salt or special pool salt (without additives such as iodine or fluoride).
3. Setting up the system
Most systems have a control that allows you to adjust chlorine production (low, medium, high). Start with the medium setting and adjust as needed.
4. Keep an eye on the pH level
The same applies to salt electrolysis: the pH value must be correct (7.2–7.6). Check it once a week with test strips and adjust if necessary.
5. Clean the cell
You should clean the electrolysis cell every 3–6 months. Limescale deposits reduce its performance. Cleaning is usually done with a mild acid solution (follow the instructions).
6. Refill salt
Salt doesn't evaporate – but it is lost when you drain water (e.g., during a water change or when topping up evaporated water). Check the salt level once a month and top up as needed.
Frequently asked questions about salt electrolysis
"Does the water taste salty?"
No. The salt concentration is approximately 3–4 g/l. For comparison: seawater has approximately 35 g/l. You cannot taste the salt.
"Isn't salt water aggressive towards metals?"
At this low concentration, it's not problematic – as long as you have high-quality, corrosion-resistant components in your hot tub. Check the manufacturer's instructions before installation.
"Do I still sometimes need to add chlorine?"
Normally no. However: In cases of very high contamination (e.g., a party with 10 people), a one-time shock chlorination may be advisable.
"Can I install the system retroactively?"
Yes, in most cases. All you need is a power source and space for the cell in the water circuit.
The conclusion regarding salt electrolysis:
Salt electrolysis is chlorine for the lazy.
It produces chlorine – but you don't have to do anything. No dosing, no calculations, no storage. The system does the work, you enjoy.
But: It costs money. And it requires a minimum of maintenance (cleaning the cell, checking the pH value).
If you are prepared to make this investment – and use your hot tub regularly – you will get the convenience that many hot tub owners regret not having bought in the first place after a year or two of manual chlorine maintenance.
Next method: Active oxygen – the chlorine-free alternative for sensitive individuals.
4. Method 3: Active oxygen – The chlorine-free alternative for sensitive individuals
Now it gets interesting.
Because active oxygen is the only method in this guide that actually produces or uses no chlorine . No chloramines. No typical swimming pool smell (which doesn't exist with properly dosed chlorine anyway, but let's leave that aside). No discussions about "chemicals".
Active oxygen sounds like what many hot tub owners are looking for: gentle, skin-friendly, odorless.
And he is.
But – and this is a big but – active oxygen has clear limitations.
If you know and accept these limitations, activated oxygen is a wonderful method. If you ignore them, you will run into problems sooner or later.
Let's talk about it honestly.
How does active oxygen work?
Active oxygen is usually based on hydrogen peroxide (H₂O₂) – a compound you may know from wound disinfection.
Hydrogen peroxide releases oxygen radicals upon contact with organic substances (bacteria, skin flakes, sweat). These radicals oxidize the cell walls of the bacteria, rendering them harmless.
The key advantage: After oxidation, hydrogen peroxide decomposes into water and oxygen. No residue. No odor. No chloramines.
Sounds perfect, right?
Almost.
The advantages of active oxygen – when skin-friendliness matters
✅ Chlorine-free and odorless – no chlorine smell, no chloramines, no arguments
✅ Very skin-friendly – ideal for people with sensitive skin, neurodermatitis or chlorine intolerance
✅ No eye irritation – no burning, even for sensitive eyes
✅ Leaves no residue – decomposes into water and oxygen
✅ Pleasant water feel – many users describe the water as “soft” and “silky”
✅ No discoloration of textiles – swimsuits do not fade
This means specifically for you:
If you are one of those people who get dry skin or red eyes after swimming in a chlorinated pool – then active oxygen is the method that can save you from that.
If you have small children and are looking for the gentlest possible solution – active oxygen is the most skin-friendly method available.
If you simply want the good feeling of using “no chemicals” (even if that’s not entirely scientifically correct, but it’s a good marketing argument) – then active oxygen is your choice.
The disadvantages of active oxygen – and why you need to know them
Now comes the part that many manufacturers are not so keen to tell you:
❌ Less effective at high temperatures – the effect decreases significantly from 28°C, and becomes critical from 35°C
❌ No long-lasting effect – breaks down quickly, needs to be reapplied frequently (before every bath)
❌ Requires an activator – usually an algaecide component that must be added weekly.
❌ Does not reliably combat algae – especially in summer or at warm temperatures
❌ More expensive to use – approximately 50–100% higher running costs than chlorine.
❌ Requires consistent maintenance – if you are ever negligent, the water will spoil faster than with chlorine.
❌ Not suitable for intensive use – active oxygen reaches its limits with a high number of bathers.
The most important point:
Active oxygen is less effective than chlorine.
That's not a flaw – it's simply physics. Hydrogen peroxide is gentler than chlorine, therefore it's kinder to the skin. But this gentleness also means it takes longer to kill bacteria. And its effectiveness decreases with heat.
Specifically, this means:
If you operate your hot tub continuously at 38–40°C (which most people do), active oxygen does not work optimally .
If you forget to add active oxygen before bathing, the water can spoil within 2-3 days.
If you're having a party with 6 people in the hot tub, active oxygen may not be enough.
Active oxygen is the gentle method – but it is less forgiving of mistakes.
For whom is active oxygen ideal?
Active oxygen is the right choice for you if:
- You have sensitive skin or react to chlorine with irritation.
- You have small children and are looking for a particularly gentle method
- Do not operate your hot tub permanently above 35°C (or are prepared to lower the temperature)
- They are prepared to maintain a disciplined and consistent routine (dosing before each bath)
- Do not use the hot tub intensively (1-2 times per week, maximum 2-3 people)
- They can accept higher ongoing costs
In short: Active oxygen is perfect for people who value skin-friendliness and are willing to accept a little more effort and expense for it.
However, if you use your hot tub frequently, operate it at high temperatures, or simply want a robust solution, then chlorine or salt electrolysis is the better choice.
How do you use active oxygen correctly?
Important note beforehand: Active oxygen requires a 2-component system :
- Active oxygen granules (hydrogen peroxide) – for disinfection
- Active oxygen activator (usually based on algaecide) – for algae protection
Without both components, the system will not function reliably.
Step-by-step instructions:
1. Check and adjust the pH value
As always, first bring the pH value to 7.2–7.6. Otherwise, even active oxygen will not work optimally.
2. Dose active oxygen granules
Add 10 g of active oxygen granules per m³ of water before each bath .
Example: For a 1,500-liter hot tub = 15 g (approx. 1 heaped tablespoon).
3. Run filtration
Run the circulation pump for at least 10 minutes to ensure the granules dissolve completely.
4. Check with test strips
Use test strips to check if the ideal value of 5–8 mg/l has been reached. If not, administer another dose.
5. Add active oxygen activator
Add 20 ml of active oxygen activator per m³ once a week – regardless of how often you bathe.
This activator prevents algae growth and stabilizes the effect of the active oxygen.
6. Perform shock treatment
Once a week you should also perform a shock treatment with a special oxidizing agent to break down organic pollutants (sweat, cosmetics).
The most common mistakes with active oxygen:
❌ Dosing too infrequently – “I just add some twice a week” is not enough. Active oxygen must be added before every bath.
❌ Forgot the activator ? Without it, you'll get algae. Guaranteed.
❌ Temperature too high – Active oxygen is overwhelmed at 40°C. Lower the temperature to 34–36°C if you wish to use this method.
❌ Never combine with chlorine ! Active oxygen and chlorine react with each other and can form dangerous gases.
Frequently asked questions about active oxygen
"Is active oxygen really 'more natural' than chlorine?"
No. Hydrogen peroxide is a chemical product just like chlorine. But it's gentler on the skin and leaves no residue. It's not "natural"—but it is skin-friendly.
"Can I heat to 40°C using active oxygen?"
It's possible – but the effect diminishes significantly. If you intend to operate it continuously above 36°C, chlorine or bromine is the better choice.
"How long can I use the water with active oxygen?"
The same duration as with chlorine – approximately 3 months, depending on usage. The formula: Water volume (liters) ÷ Number of bathers per day ÷ 12 = Days until water change.
"Does active oxygen have no smell at all?"
Correct. Hydrogen peroxide has no odor of its own. If your water smells of active oxygen, something is rotten (literally).
"Is activated oxygen dangerous?"
Not at the concentration used (5–8 mg/l). But as with all personal care products: Do not swallow, avoid contact with eyes, keep away from children.
The conclusion regarding active oxygen:
Active oxygen is the gentlest method – and at the same time the most demanding .
It is perfect for people with sensitive skin, chlorine intolerance, or small children. It is skin-friendly, odorless, and leaves no residue.
However, it requires discipline. It doesn't forgive negligence. And it doesn't work optimally at high temperatures.
If you are prepared to accept these limitations – and to consistently dose before each bath – then active oxygen is a wonderful alternative.
If you don't feel confident doing that, or if you want to operate your hot tub at 38–40°C – then stick with chlorine.
Next method: Bromine – the low-odor disinfection for heat lovers.
5. Method 4: Bromine – Low-odor disinfection for heat lovers
Bromine is the quiet specialist among disinfection methods.
Not as well-known as chlorine. Not as hyped as active oxygen. Not as modern as salt electrolysis.
But: Bromine has a clear target group – and for this target group it is often the best choice.
For whom?
For anyone who operates their hot tub at high temperatures (38–40°C), uses it frequently (daily or several times a week) and doesn't want a typical swimming pool smell.
Does this sound like you? Then read on.
How does bromine work?
Bromine disinfects according to the same principle as chlorine: it oxidizes the cell walls of bacteria, viruses and fungi.
The big difference: Bromine is more stable at high temperatures and less odorous than chlorine.
While chlorine slowly loses its effectiveness at 38–40°C (which is why you need more of it), bromine remains reliably effective even at these temperatures.
The second difference: Bromine does not form bromines (the counterpart to chloramines), which cause unpleasant odors. Even if the water is heavily contaminated, it barely smells.
The third difference: Bromine is less dependent on pH than chlorine. While chlorine loses significant effectiveness at pH values above 7.6, bromine disinfects reliably even at pH values up to 8.0.
This makes bromine the perfect choice for anyone who doesn't want to – or can't – be too precise with pH control.
The advantages of bromine – when heat and comfort matter
✅ Low odor – no typical swimming pool smell, even with intensive use
✅ Stable at high temperatures – works best at 38–40°C
✅ Less pH-dependent – still works reliably even at pH values up to 8.0
✅ Slow-dissolving tablets – longer depot effect, less frequent need for redosing.
✅ No bromine formation – no unpleasant odors from contact with organic substances
✅ Gentle on the skin – many users find bromine more pleasant than chlorine.
This means specifically for you:
If you are one of those people who use their hot tub daily – a round in the morning before work, in the evening after sports – then Brom is the method that offers you reliability with minimal maintenance .
You don't need to worry daily about whether you've added enough disinfectant. The slow-dissolving bromine tablets release the active ingredient continuously over 10–14 days.
You don't need to adjust the pH level precisely every week. Bromine can tolerate a pH of 7.8 – chlorine cannot.
And you don't have to deal with any unpleasant smells. Even if you get into the hot tub sweaty after a long day, the water remains odorless.
Bromine is the method for frequent users who value comfort.
The disadvantages of bromine – because honesty counts here too
Bromine sounds perfect? Almost. But there are a few things you should know beforehand:
❌ More expensive than chlorine – bromine tablets cost approximately 30–50% more than chlorine tablets.
❌ Dissolves slowly – not suitable for rapid shock chlorination (you will still need chlorine for that)
❌ Accumulates in water – bromine is not completely broken down and accumulates over time.
❌ Not UV-stable – in outdoor hot tubs during the summer, the effectiveness may decrease due to sun exposure.
❌ More difficult to break down – if you want to switch from bromine to another method, you have to completely replace the water.
❌ Requires special dosing aids – tablets should not be placed directly into the water, but into a dosing float or filter box.
The most important point:
Bromine is an investment in comfort – but it will cost you more in the long run than chlorine.
Calculation example:
- Chlorine: approx. 200–300 euros per year (with regular use)
- Bromine: approx. 350–450 euros per year (with the same usage)
That's not a huge difference – but over 5 years that's an extra 250–750 euros.
If you consider these additional costs worthwhile for low-odor and stable disinfection at high temperatures – then bromine is the right choice for you.
If you want to save money and don't have a problem with the smell of chlorine (which doesn't occur with correct dosage anyway) – then stick with chlorine.
For whom is bromine ideal?
Bromine is the right choice for you if:
- You use your hot tub frequently (daily or several times a week)
- bathe them permanently at high temperatures (38–40°C)
- They don't want any smell – even with intensive use.
- They value low maintenance (pH value does not need to be corrected as often)
- They are willing to invest a little more (approx. 30–50% higher running costs)
- Operate your hot tub under a roof or indoors (for outdoor hot tubs, UV radiation can reduce the effectiveness in summer)
In short: Bromine is the perfect method for frequent users who operate their hot tub at high temperatures and value low-odor, comfortable water care.
However, if you only use your hot tub 1-2 times per week or want to save money, then chlorine is the better choice.
How do you use bromine correctly?
Important note: Bromine tablets should never be added directly to the water . They can cause bleach stains on the bathtub material.
Use either:
- A dosing float (floats on the water surface, slowly releases bromine)
- The filter box (if your hot tub has a suitable dosing system)
- A tablet dosing chamber (already built into some hot tubs)
Step-by-step instructions:
1. Check and adjust the pH value
The same applies to bromine: the pH value should be within the ideal range (7.2–7.6). While bromine can tolerate deviations up to 8.0, it works best within this ideal range.
2. Dosage of bromine tablets
Basic dosage: Add 3–4 bromine tablets per m³ every 10–14 days to the dosing float or filter box.
Example: For a 1,500-liter hot tub = 4–6 tablets.
3. Run the filtration process
Run the circulation pump for several hours (ideally overnight) to ensure the bromine is evenly distributed.
4. Check with test strips
After 12–24 hours, check with test strips whether the ideal value of 3.0–5.0 mg/l has been reached.
Important: The ideal value for bromine is higher than for chlorine (1.0–1.5 mg/l). This is normal – bromine works just as reliably at higher concentrations without being more aggressive.
5. Add more dose if needed.
If the value is too low, add 1-2 more tablets and check again after 12 hours.
6. Perform shock treatment
Despite using bromine, you should perform a shock treatment with chlorine granules once a week to reduce organic pollutants (sweat, cosmetics).
Dosage: 5–10 g chlorine granules per m³, run filtration for 10 minutes.
Don't worry: This one-time addition of chlorine does not impair the effect of the bromine. It complements it.
The most common mistakes with bromine:
❌ Throwing tablets directly into the water – causes bleach spots. Always use a floating dispenser or filter box.
❌ Dosing too little – The ideal value is 3.0–5.0 mg/l, not 1.0–1.5 mg/l as with chlorine.
❌ Forgot shock treatment – Even with bromine, you need oxidation with chlorine granules once a week.
❌ Outdoor hot tub in the sun – UV radiation breaks down bromine faster. Use a cover or replenish the bromine more frequently.
Frequently asked questions about bromine
"Is bromine 'gentler' than chlorine?"
Many users find bromine more pleasant – but that's subjective. Chemically speaking, bromine isn't inherently "gentler." It simply smells less and is more stable at high temperatures.
"Can I switch from chlorine to bromine?"
Yes, but: You should completely replace the water beforehand. Chlorine and bromine should not be mixed.
"Why do I still have to use chlorine for shock treatment?"
Bromine oxidizes bacteria – but it doesn't break down organic contaminants (sweat, grease, cosmetics) as effectively as chlorine. Therefore, a chlorine shock treatment once a week is recommended.
"Does bromine also work in outdoor hot tubs?"
Yes, but: In summer, UV radiation can reduce the effectiveness. Use a cover when the hot tub is not in use – or replenish the solution more frequently.
"How long does a bromine tablet last?"
Depending on water temperature and usage, one tablet dissolves in 3–5 days. Therefore, the recommendation is: 3–4 tablets every 10–14 days.
"Is bromine more environmentally friendly than chlorine?"
No. Bromine is just as much a chemical disinfectant as chlorine. It simply breaks down more slowly – which is rather a disadvantage for the environment.
The conclusion regarding bromine:
Bromine is the specialist for frequent users and heat lovers.
Do you use your hot tub daily at 38–40°C? Do you want to avoid odors? Do you not want to worry about the pH level every week?
Then bromine is your method.
It costs you a little more than chlorine – but in return you get reliability, stability at high temperatures and low-odor water care.
However, if you only use your hot tub occasionally, want to save money, or have an outdoor hot tub in direct sunlight, then chlorine or salt electrolysis is the better choice.
Now you've learned about all four methods. Time for the most important question:
Which method suits you best?
We'll clarify that in the next chapter: The comparison table.
6. Comparison table: Which method suits you best?
You have now learned about all four methods: chlorine, salt electrolysis, active oxygen, and bromine.
Each has its place. Each works – under the right conditions.
The question is not: "What is the best method?"
The question is: "What suits me, my hot tub and my everyday life?"
This overview will help you with exactly that.
The compact comparison table
| criterion | chlorine | Salt electrolysis | Active oxygen | bromine |
|---|---|---|---|---|
| effectiveness | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐⭐ |
| skin friendliness | ⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ |
| Odor | ⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ |
| Costs (acquisition) | ⭐⭐⭐⭐⭐ | ⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ |
| Costs (consumption) | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐ |
| Time required | ⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐ | ⭐⭐⭐⭐ |
| Heat resistance (38-40°C) | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐ | ⭐⭐⭐⭐⭐ |
| It forgives negligence | ⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐ | ⭐⭐⭐⭐ |
| For intensive use | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐ | ⭐⭐⭐⭐⭐ |
The detailed decision-making aid
Tables are all well and good – but sometimes you just need a clear statement:
"If you are X, then take Y."
That's exactly what you'll get now.
Scenario 1: The pragmatic heavy user
Your situation:
- You use your hot tub 3-5 times per week
- They don't want to spend much time on water care.
- They want a reliable, proven solution.
- Budget is more important than maximum comfort.
Your best choice: Chlorine
Why?
Chlorine is the most reliable, affordable, and proven method. You invest 10 minutes per week – and have crystal-clear water. No expensive equipment, no complicated systems, it simply works.
Alternatively: If you are willing to invest 1,000–2,000 euros, salt electrolysis is the comfort-upgrade version of chlorine.
Scenario 2: The Comfort Lover
Your situation:
- You use your hot tub daily or almost daily
- They don't want to deal with water care.
- They are ready to invest in a facility.
- They plan to use the hot tub for at least 5 years.
Your best choice: Salt electrolysis
Why?
You add salt to the water once, and the system does the rest. No dosing, no calculating, no wondering "Did I add enough?". The system costs €1,000–€2,000 – but the investment pays for itself from year 3–4 onwards. And you gain: time. And peace of mind.
Scenario 3: The sensitive person (or the family with small children)
Your situation:
- They have sensitive skin or react to chlorine with irritation.
- They have small children and want the gentlest method.
- They tend to use the hot tub at moderate temperatures (32–36°C).
- They are prepared to provide disciplined and consistent care.
Your best choice: Active oxygen
Why?
Active oxygen is the most skin-friendly method available. Odorless, no eye irritation, gentle on the skin. However, it requires discipline. You have to dose it before each bath – and you shouldn't keep the temperature consistently above 35°C. If you can accept that: perfect.
Important: If you want to bathe at 38–40°C despite having sensitive skin, try chlorine with an optimally adjusted pH value first. Most skin irritations are caused by an incorrect pH value, not by chlorine.
Scenario 4: The Heat Junkie
Your situation:
- They bathe exclusively at 38–40°C
- They use the hot tub daily or several times a week
- They don't want any smell
- They are willing to invest a little more.
Your best choice: Bromine
Why?
Bromine is the specialist for high temperatures. While chlorine slowly loses its effectiveness at 40°C, bromine performs at its best. Low odor, stable, reliable. It costs 30–50% more than chlorine – but in return, you get exactly what you want: Daily bathing at 40°C without odor and with minimal maintenance.
Scenario 5: The casual user
Your situation:
- They use the hot tub 1-2 times per week.
- They don't want high ongoing costs.
- They have no special requirements (no chlorine allergy, no excessive heat).
Your best choice: Chlorine
Why?
For infrequent use, neither a salt electrolysis system (too expensive for the frequency of use), nor bromine (too expensive to run), nor active oxygen (too complex for occasional use) is worthwhile. Chlorine is inexpensive, reliable, and perfect for occasional users.
Scenario 6: The family with teenagers (= party hot tub)
Your situation:
- The hot tub is used intensively – often by several people at the same time.
- Sometimes 5-6 people get in at the same time
- You need a robust solution that also works under high stress.
Your best choice: chlorine or salt electrolysis
Why?
For intensive use by many people, chlorine is the most reliable method. Active oxygen is overwhelmed by such loads, and bromine would be too expensive. If you are willing to invest in a system: salt electrolysis automatically produces enough chlorine, even for party use.
The ultimate decision-making tool: The flowchart
Still unsure? Then answer these three questions:
Question 1: Do you have sensitive skin or a chlorine allergy?
- Yes → Go to question 2
- No → Go to question 3
Question 2: Are you prepared to dose carefully before each bath?
- Yes → Active oxygen (but only at temperatures below 36°C)
- No → Bromine (gentler than chlorine, less effort required than active oxygen)
Question 3: Are you prepared to invest 1,000–2,000 euros in an investment?
- Yes → Go to question 4
- No → Go to question 5
Question 4: Do you use the hot tub at least 3-4 times per week?
- Yes → Salt electrolysis (maximum comfort, pays off in the long run)
- No → Chlorine (reliable and inexpensive)
Question 5: Do you bathe exclusively at 38–40°C and use the hot tub daily?
- Yes → Bromine (specialized for high temperatures)
- No → Chlorine (the tried and tested standard solution)
The conclusion: There is no "best" method – only the appropriate one.
If you have read this far, you understand:
Water care is not a religion.
It's not about whether chlorine is "bad" or active oxygen is "good". It's not about marketing promises or hype.
It's about three simple questions:
- What do I want? (Comfort, skin-friendliness, low odor, affordable?)
- How do I use my hot tub? (Daily, occasionally, in high temperatures?)
- What am I willing to invest? (Time, money, discipline?)
If you answer these three questions honestly, you will know which method suits you best.
And then in the evening you can open the cover, get into the water – and think of nothing but:
"That's exactly why I got it."
In the next chapter I will show you: The 6 rules for perfectly maintained water – no matter which method you choose.
7. The water care routine: 6 rules for carefree relaxation
Now it gets practical.
They've chosen a disinfection method. Good. But even the best method in the world won't work if the basics aren't right.
And the good news: These basics are simple.
No rocket science. No chemistry lecture. Six clear rules.
If you follow these six rules – regardless of whether you use chlorine, salt, active oxygen, or bromine – you'll have crystal-clear water. Guaranteed.
If you ignore any of these, you will run into problems sooner or later. Guaranteed.
So, let's focus on what really matters.
Rule 1: Balance your water
First things first: The pH value is more important than the disinfectant.
Read that again.
The pH value is more important than the disinfectant.
You can use the most expensive chlorine granules in the world – if the pH is 8.2, it will barely disinfect. You can have the best salt electrolysis system – at pH 7.8, it will produce significantly less chlorine.
The pH value is the foundation. Without the correct foundation, nothing works.
Ideal range: 7.2 – 7.6
What happens if the pH level is incorrect?
| pH value too low (<7.0) | pH value too high (>7.6) |
|---|---|
| Water becomes acidic | Disinfectants are less effective |
| Corrosion on metals | Limescale deposits form |
| Skin irritation, burning eyes | Filters get dirty faster |
| Disinfectant is used up faster | The water becomes cloudy. |
Specifically, this means:
The vast majority of problems in hot tubs – cloudy water, skin irritation, unpleasant odor – are caused by incorrect pH levels, not by too little disinfectant.
Here's how to regulate the pH level:
1. Measurement: Use test strips (available for 10–15 euros, last for six months). Immerse the strip in water for 1 second, wait 15 seconds, and compare with the color scale.
2. Regulate:
- pH too low? → Add pH increaser (pH Plus), usually in granular form.
- pH too high? → Add pH reducer (pH minus), usually in granular form.
3. Remeasure: Measure again after 15 minutes, readjust if necessary.
How often? At least once a week. When refilling, daily for the first week (warm water tends to raise the pH level).
Pro tip: If your pH level fluctuates constantly, it's usually due to insufficient alkalinity (TA value). More on that in a moment.
Alkalinity (TA value): The invisible helper
Alkalinity acts as a pH buffer. It stabilizes the pH value and prevents extreme fluctuations.
Ideal range: 80 – 120 mg/l
What happens if the alkalinity is too low?
The pH level is fluctuating wildly. Today it's 7.2, tomorrow 7.8, the day after tomorrow back to 7.0. They can't keep up with the regulation.
What happens if the alkalinity is too high?
The pH level is difficult to lower. You add pH reducer – and hardly anything happens.
Here's how to regulate alkalinity:
1. Measuring: Using test strips (most show pH value AND alkalinity)
2. Regulate:
- TA value too low? → Add alkalinity increaser (Alka-Plus).
- TA value too high? → Add pH reducer (pH Minus) in several small steps.
How often? Check and adjust immediately after refilling. Then check once a month.
The correct order:
- First adjust the alkalinity (TA value 80–120 mg/l)
- Then adjust the pH value (7.2–7.6)
- Only add disinfectant after that.
Those who ignore this order will struggle against fluctuating values their entire lives.
Hardness stabilization: Avoid limescale
If you live in a region with hard water (over 200 mg/l total hardness – check with your water supplier), you should add a hardness stabilizer (e.g., Kalk-Ex) immediately after refilling.
Why?
At high temperatures (38–40°C), limescale precipitates from the water and deposits on walls, nozzles, and heating elements. This leads to:
- Rough surfaces
- Clogged nozzles
- Reduced lifespan of the heating system
Dosage: According to the manufacturer, usually 100–200 ml per m³ for hard water.
How often? Every time it's refilled, otherwise not necessary.
Rule 2: Perform a basic treatment weekly.
Even if you disinfect daily, you need a shock treatment once a week.
Why?
Because organic substances accumulate over the course of the week, which normal disinfectant does not completely break down:
- sweat
- Skin oils
- Cosmetics (sunscreen, body lotion)
- Hair products
These substances bind free chlorine (= chloramines) or weaken the effect of other disinfectants.
The solution: shock chlorination
Even if you are working with active oxygen or bromine, you should perform a shock chlorination once a week.
Here's how:
Product: Fast-dissolving chlorine granules or special oxidizing agent (e.g., "Water-Clean")
Dosage:
- For chlorine granules: 10–15 g per m³
- For special oxidizing agents: According to the manufacturer's instructions (usually 1 bag per m³)
Application:
- Add the granules directly to the water.
- Run filtration for 15–30 minutes
- You can bathe again after 15 minutes (with most products).
When? Once a week, ideally always on the same day (e.g. every Sunday evening)
Why this is so important:
Without weekly shock treatment, the following will occur:
- Chlorine odor (from chloramines)
- Eye irritation
- Murky water
- Slippery walls
Those 10 minutes a week will save you hours of problem-solving.
Rule 3: Disinfect the water effectively
You already learned about this in detail in Chapter 2. Here's the summary:
Chlorine:
- Add 5 g of granules per m³ after each bath OR
- Add 1 tablet (20 g) per m³ to the filter box every 7 days.
- Ideal value: 1.0–1.5 mg/l
Salt electrolysis:
- Add 3–4 kg of salt per 1,000 liters once.
- The system runs automatically.
- Check pH level once a week
Active oxygen:
- Add 10 g of granules per m³ before each bath.
- Add 20 ml of activator per m³ once a week.
- Ideal value: 5–8 mg/l
Bromine:
- 3–4 tablets per m³ every 10–14 days in a dosing float
- Ideal value: 3.0–5.0 mg/l
Important: Disinfectants only work optimally at the correct pH value (7.2–7.6). Always check the pH value first, then disinfect.
Rule 4: Filter the water sufficiently
The filter is your invisible helper. It traps dirt particles, hair, and skin flakes – and keeps them out of the water.
But: A filter only works if it is clean.
How long should the filter pump run?
Rule of thumb: 4–8 hours per day, depending on usage
- With daily use: 6–8 hours
- For occasional use: 4–6 hours
Most hot tubs have programmable filter pumps. Set them to run automatically – you don't have to worry about it.
Clean the filter cartridge:
How often? Every 4 weeks
Here's how:
- Remove the cartridge from the filter box
- Rinse off coarse dirt with a garden hose.
- Place in a bucket with 5 liters of water + filter cleaner (100–200 g).
- Leave to soak for 5 hours (overnight for heavy soiling)
- Rinse, let dry, reinsert.
How often should I replace it? Every 1–2 years, depending on usage.
Symptoms of a dirty filter:
- Water remains cloudy despite disinfection.
- The pump is running louder than usual.
- Water pressure at the nozzles decreases
Pro tip: Buy a second filter cartridge. Then you can clean and dry the dirty cartridge at your leisure while the clean one is in use.
Rule 5: Change the water regularly
Even the best disinfectant doesn't last forever. Over time, substances accumulate in the water that cannot be filtered or broken down:
- minerals
- Salts (even without salt electrolysis)
- Chemical residues
- Dissolved organic substances
The water becomes "used up" – it looks lifeless, foams faster, and disinfectants are less effective.
When should you change the water?
Rule of thumb:
Water volume (liters) ÷ Number of bathers per day ÷ 12 = Days until water change
Examples:
- Hot tub with 1,500 liters, 2 people daily → 1,500 ÷ 2 ÷ 12 = 62 days (approx. 2 months)
- Hot tub with 1,200 liters, 4 people daily → 1,200 ÷ 4 ÷ 12 = 25 days (approx. 1 month)
The water should be changed at least every 3 months – no matter how often you bathe.
What to do when changing the water.
1. Clean the pipe system:
Before draining: Add special pipe cleaner (e.g. "System-Rein"), run filtration for 15 minutes, then drain.
Why? Biofilms – bacteria, algae, and organic matter – accumulate in the pipes over months. These deposits consume disinfectants and lead to water problems.
2. Drain the water:
Use the drain plug or pump out the water (faster with a submersible pump).
3. Clean surfaces:
Wipe all surfaces with surface cleaner and a soft sponge. Do not use abrasive cleaners – they will scratch the surface.
4. Refill:
Fill with fresh tap water.
5. Adjust water balance:
- Add water hardness stabilizer (for hard water)
- Adjust alkalinity (TA value 80–120 mg/l)
- Adjust pH value (7.2–7.6)
- Add disinfectant
6. Clean the cover:
Take this opportunity to clean the cover as well (top and bottom).
Rule 6: Maintain the water according to plan
Here's the hard truth:
The best water care method in the world won't work if you don't apply it consistently.
But: Consistency doesn't require perfection. Consistency requires routine.
The 10-minute weekly routine:
Every Sunday (or another fixed day):
✅ 5 minutes: Measure pH value with test strips, adjust if necessary.
✅ 2 minutes: Measure disinfectant level, re-dose if necessary
✅ 3 minutes: Perform shock chlorination (add granules, start filtration)
That's it. 10 minutes per week.
Each month (in addition):
✅ 10 minutes: Clean filter cartridge
✅ 2 minutes: Check alkalinity (TA value), adjust if necessary
Every 2–3 months (in addition):
✅ 30 minutes: Change the water completely (see above)
The service plan for printing:
| Task | How often? | Time required |
|---|---|---|
| Measuring and regulating pH levels | once a week | 5 min. |
| Re-dosage disinfectant | After every bath or once a week | 2 min. |
| Perform shock chlorination | once a week | 3 min. |
| Clean the filter cartridge | once a month | 10 min. |
| Check alkalinity | once a month | 2 min. |
| Change all water | Every 2–3 months | 30 min. |
Total: 10 minutes per week + 12 minutes per month + 30 minutes every 2-3 months
That's an average of 15 minutes per week.
Less time than it takes to watch a series on Netflix.
The conclusion: Routine beats perfection
You don't need to be a chemist. You don't need to be a water care expert.
You just need to follow these six rules – consistently, but without striving for perfection.
If you do that, you will never experience again:
- Murky water
- Unpleasant odors
- Slippery walls
- Skin irritations
- The frustration when you want to relax after work – and the water is unusable.
Instead, you will experience:
Open the cover in the evening. Step into the crystal-clear water. Close your eyes. And think of nothing but:
"That's exactly why I got it."
In the next chapter: The most common water problems and their solutions – in case something does go wrong.
8. Common water problems and their solutions – if something does go wrong
Even with the best routine, it can happen.
You open the cover – and the water looks like a latte. Or it smells strange. Or the walls feel slippery like a slide in a swimming pool.
No panic.
The vast majority of water problems are not dramatic. They are merely symptoms of one of the six fundamental pillars (see Chapter 4) being wrong.
The good news: Almost every problem can be solved in 10–30 minutes.
Even better: If you know the cause, it won't happen a second time.
Problem 1: Cloudy, milky water
Symptom:
The water looks like milk. You can't see to the bottom. It seems "dead" or "lifeless".
What happened?
Cloudy water has three common causes:
Cause 1: Too little disinfectant in the water
Bacteria and organic matter multiply unchecked. They are too small to be captured by the filter – but numerous enough to make the water cloudy.
Cause 2: Incorrect pH value (usually too high)
If the pH value is above 7.8, limescale particles can precipitate and cloud the water. At the same time, disinfectants are less effective – which exacerbates cause 1.
Cause 3: Dirty filter
A clogged filter can no longer retain dirt particles. They circulate in the water and make it cloudy.
The solution:
Step 1: Check and correct the pH value
Measure the pH value using test strips. Is it above 7.6? Then add pH reducer (pH Minus) until the value is between 7.2 and 7.6.
Wait 15 minutes, measure again.
Step 2: Perform shock chlorination
Add 15–20 g of chlorine granules per m³ of water (twice the normal dosage). This also applies if you normally work with active oxygen or bromine.
Let the filtration run for at least 30 minutes.
Step 3: Check and clean the filter
Remove the filter cartridge. Is it dirty? If so, clean it thoroughly (see Rule 4, Chapter 4) or replace it.
Step 4: Add flocculant (optional)
If the water is still cloudy after 24 hours, add a flocculant (e.g., "Crystal Clear"). This binds microscopically small suspended particles into larger particles that the filter can then capture.
Dosage: According to the manufacturer's instructions, usually 20–30 ml per m³.
Step 5: Wait and measure again
After 24 hours, the water should be clear again. Measure the pH and disinfectant levels again – and make sure both values are within the ideal range.
How can you avoid this in the future?
✅ Check pH level once a week
✅ Consistently reapply disinfectant
✅ Clean the filter cartridge every 4 weeks
✅ Perform shock chlorination once a week
Problem 2: Green water (algae infestation)
Symptom:
The water has a greenish tint. The walls feel slippery. In the worst case, you'll see green streaks on the walls.
What happened?
Algae. They have multiplied in the water because the disinfectant level was too low – or because you are using active oxygen (which does not reliably combat algae).
Important: Green water is not dangerous. Algae are not pathogens. But they are unpleasant – and a sign that the water treatment is not working.
The solution:
Step 1: Correct the pH value
As always: First, bring the pH value to 7.2–7.6. Otherwise, the subsequent treatment will only be half as effective.
Step 2: Shock chlorination – but done right
Add 30–40 g of chlorine granules per m³ (that's 3–4 times the normal dose). This will kill the algae.
Let the filtration run for at least 2 hours.
Step 3: Add algaecide (optional)
If you are using active oxygen or frequently struggle with algae, add an algicide (algae protectant) as well.
Dosage: According to the manufacturer's instructions, usually 50–100 ml per m³.
Step 4: Clean or replace the filter
The dead algae are trapped by the filter. Clean the filter cartridge thoroughly – or replace it if it is heavily soiled.
Step 5: Change the water if necessary
If the water is still green after 48 hours despite shock chlorination, the algae infestation is too severe. The only solution is to completely drain the water, thoroughly clean the surfaces, and refill.
How can you avoid this in the future?
✅ If you are using active oxygen: Add algaecide (activator) weekly.
✅ Always keep disinfectant levels within the ideal range
✅ Perform shock chlorination once a week
✅ For outdoor hot tubs: Keep the cover closed when not in use (sunlight promotes algae growth)
Problem 3: Strong chlorine odor and eye irritation
Symptom:
The water has a strong, unpleasant swimming pool smell. My eyes burn. My skin itches after swimming.
What happened?
The paradox: There is too little chlorine in the water, not too much.
Do you remember? The typical "chlorine smell" is caused by chloramines – compounds of chlorine and organic substances (sweat, skin oils, cosmetics).
Chloramines are formed when there is too little free chlorine to completely break down these organic substances.
Additionally: If the pH value is too high, chlorine has a weaker effect – and even more chloramines are formed.
The solution:
Step 1: Correct the pH value
Measure the pH value. Is it above 7.6? Then lower it to 7.2–7.4 using pH reducer.
Step 2: Perform shock chlorination
Add 20–30 g of chlorine granules per m³. This destroys the chloramines through oxidation.
Let the filtration run for 30 minutes.
Important: Do not swim again until the chlorine level is below 5 mg/l (after approximately 2–4 hours). Measure using test strips.
Step 3: Establish weekly pulse therapy
Chloramines develop gradually. The best prevention: shock chlorination once a week, even if the water "looks fine".
How can you avoid this in the future?
✅ Maintain pH within the ideal range (7.2–7.6)
✅ Always keep free chlorine between 1.0–1.5 mg/l
✅ Perform shock chlorination once a week
✅ Shower before bathing (reduces organic load)
Problem 4: Foam formation on the water surface
Symptom:
When you turn on the jets, a thick foam forms on the water's surface, like soap scum in a bathtub.
What happened?
Foam is created by organic substances in the water that change the surface tension:
- Soap or shower gel residue on the skin
- Body lotions, sunscreen
- Hair care products
- detergent residue in swimwear
The more organic matter present, the more foam.
The solution:
Short-term solution: Add foam remover.
There are special antifoaming agents (e.g., "Foam-Ex") that restore surface tension.
Dosage: According to the manufacturer's instructions, usually 20–30 ml per m³.
Important: Foam-Ex only treats the symptom, not the cause. If the water is still foamy after adding it, the organic load is too high → change the water.
Long-term: Reduce organic load
✅ Shower thoroughly before bathing (without soap – only with water)
✅ Wash off cosmetics (body lotion, sunscreen) before bathing
✅ Wash swimwear without fabric softener before first use.
✅ Perform shock chlorination once a week (breaks down organic matter)
How can you avoid this in the future?
✅ Shower before every bath
✅ No cosmetics in the hot tub
✅ Shock chlorination once a week
✅ Change the water every 2–3 months
Problem 5: Limescale deposits or cloudy, milky water with white flakes
Symptom:
The water has a whitish sheen. You can see white flakes floating in the water. A rough, white crust forms on the walls, jets, and at the water's edge.
What happened?
Limescale precipitation.
If you live in a region with hard water (over 200 mg/l total hardness) and heat the water to 38–40°C, limescale will precipitate out of the water.
Additional benefits from:
- pH value above 7.6 (promotes limescale precipitation)
- Alkalinity above 120 mg/l
The solution:
Step 1: Lower the pH level
Lower the pH value to 7.2–7.4 using pH Minus. This will stop further limescale precipitation.
Step 2: Add hardness stabilizer
Add a water hardness stabilizer (e.g., "Limescale Remover"). This binds the limescale in the water and prevents it from depositing on surfaces.
Dosage: According to the manufacturer's instructions, usually 100–200 ml per m³.
Step 3: Clean the filter
The filter traps the precipitated limescale particles. Clean the filter cartridge thoroughly.
Step 4: Clean surfaces
If limescale deposits have already formed on walls or nozzles, remove them with a special limescale remover or with vinegar water (diluted 1:1).
Do not use: Abrasive cleaners or hard brushes – these will scratch the surface.
How can you avoid this in the future?
✅ Add water hardness stabilizer immediately after each refill (for hard water)
✅ Maintain pH within the ideal range (7.2–7.6)
✅ Do not allow alkalinity to rise above 120 mg/l
Problem 6: Slippery, slimy walls (biofilm)
Symptom:
The walls feel slippery, as if you were wiping a layer of soap. In the worst case, you'll see brown or black stains.
What happened?
Biofilm.
This is a layer of bacteria, algae, and organic matter that has accumulated on surfaces and in pipes.
Biofilm forms when:
- Too little disinfectant in the water is
- The water hadn't been changed for too long
- The pipes were never cleaned
Important: Biofilm is persistent. Normal disinfectants cannot reach it because it is shielded by a protective layer.
The solution:
Step 1: Clean the pipe system
Add a special pipe cleaner (e.g., "System-Rein") to the water. This will dissolve the biofilm in the pipes.
Dosage: According to the manufacturer's instructions, usually 1 sachet per m³.
Let the filtration run for 15–30 minutes. Then drain the water completely.
Step 2: Clean surfaces thoroughly
Wipe all surfaces with a surface cleaner and a soft sponge. Pay particular attention to corners, nozzles, and the waterline.
Step 3: Refill and restore water balance
Top up with fresh water and adjust pH, alkalinity and disinfectant levels correctly (see Rule 1, Chapter 4).
Step 4: Replace the filter cartridge
Biofilm can also accumulate in the filter. Replace the filter cartridge – cleaning alone is not enough.
How can you avoid this in the future?
✅ Always keep disinfectant in the ideal range
✅ Perform shock chlorination once a week
✅ Change the water every 2–3 months
✅ Flush the pipe system with pipe cleaner every time the water is changed.
The emergency checklist: What to do if you don't know what to do next.
If the water has a problem that you cannot identify, work through this list:
1. Check and correct the pH value (7.2–7.6)
→ 80% of all problems are caused by incorrect pH value
2. Check and correct disinfectant levels (chlorine 1.0–1.5 mg/l, bromine 3.0–5.0 mg/l, active oxygen 5–8 mg/l)
→ Insufficient disinfection is the second most common cause
3. Perform shock chlorination (20–30 g of chlorine granules per m³)
→ Oxidizes organic pollutants and chloramines
4. Clean or replace the filter
→ A dirty filter exacerbates almost every problem.
5. Change the water (if nothing else helps)
→ Sometimes the water is simply "used up"
In 95% of cases, the problem is solved after steps 1-4.
The conclusion: Problems are normal – panic is not.
Every hot tub owner experiences one of these problems sooner or later. That's normal.
The important thing is: you now know what to do.
Cloudy water? Check pH level, shock chlorinate, clean filter.
Chlorine smell? Shock chlorination.
Foam? Shower off, use foam remover, reduce organic load.
Limescale? Use a water hardness stabilizer to lower the pH value.
Biofilm? Clean the pipe system, change the water.
They are not helpless. They have solutions.
And if you consistently follow the six basic rules from Chapter 4, you will never experience most of these problems.
In the next chapter: The big conclusion – Which method is right for you now?
9. Conclusion: Good water care is the foundation for carefree relaxation.
If you've read this far, you now know more about water care than 90% of all hot tub owners.
They know why chlorine has an undeservedly bad reputation – and why it is the best choice for most people.
You know the alternatives: salt electrolysis for maximum comfort. Active oxygen for sensitive skin. Bromine for those who love heat.
They have internalized the six basic rules: pH value, shock treatment, disinfection, filter, water change, routine.
And you know what to do if something does go wrong.
But the most important thing is something else:
Water care is not an end in itself.
You don't buy a hot tub to become a chemist.
You don't buy a hot tub to worry about pH levels, chloramines, and filter cleaning.
They buy a hot tub to unwind after a long day.
To sit in warm water with a cup of coffee in the morning and start the day.
To let your shoulders drop under the starry sky in the evening and think of nothing but: "That's exactly why I got this."
Good water care is the foundation that makes this moment possible every day.
Not even once a month. Not just if you've spent two hours beforehand dealing with test strips and granules.
Every day. Without a second thought. Without ifs, ands, or buts.
That's the difference between a hot tub you use and a hot tub you love.
The one decision that makes everything easier
Here's the good news:
You don't have to make a perfect decision right now.
You just need to make one decision – and then stick to it.
Chlorine, salt, active oxygen or bromine – all four methods work.
The question is not: "What is objectively the best?"
The question is: "What suits me?"
- Do you want a proven and affordable option ? → Chlorine
- Do you want maximum comfort and are you ready to invest? → Salt electrolysis
- Do you have sensitive skin and are you ready for disciplined skincare? → Active oxygen
- Do you bathe daily at 40°C and want to avoid odors? → Bromine
None of these decisions are wrong.
The only wrong thing to do is: not to make a decision. Or to make a decision – and then implement it half-heartedly.
A consistently implemented "second-best" method is better than a perfect method that you only use irregularly.
What you now know – and what most hot tub owners don't know
Most people buy a hot tub and are handed a bag of chemicals by the dealer.
"Add this when the water becomes cloudy."
"Check the pH level from time to time."
"Call us if you have any problems."
That's it.
No system. No routine. No explanation of why things happen.
They are now in a different position.
You know:
- Why pH value is more important than disinfectant
- Why "chlorine smell" actually means "too little chlorine"
- Why a weekly shock treatment prevents 80% of all problems
- Why a dirty filter ruins even the best water care
- Why water changes are not optional, but essential
This knowledge is the difference between:
"My hot tub is nothing but trouble"
and
"My hot tub is the best thing I've ever bought."
The most important piece of advice comes last.
If you take away only one thing from this guide, let it be this:
Establish a routine – and stick to it.
Not perfect. Not overly precise. Simply consistent.
Every Sunday, 10 minutes:
- Measure pH value
- Check disinfectant
- Perform shock chlorination
An additional 10 minutes each month:
- Clean filter
- Check alkalinity
Every 2-3 months, plus an additional 30 minutes:
- Change water
- Clean the pipe system
- Cleaning surfaces
That's it.
No rocket science. No hours-long procedures. Simply: routine.
And if you stick to this routine, I promise you:
You will never again experience coming home in the evening, looking forward to the hot tub – and then being frustrated by murky water or unpleasant smells.
Instead, you will experience:
Every evening, open the cover. Step into the clear water. Close your eyes. And think: "Exactly for this."
Your next steps
You now have the knowledge. Time to put it into practice.
Step 1: Choose a disinfection method
Go back to Chapter 3, reread the decision aid – and make a decision.
Not a perfect one. Just one.
Step 2: Obtain the basic equipment
What you absolutely need:
- ✅ Test strips (for pH value, alkalinity, disinfectant)
- ✅ pH regulator (pH Plus and pH Minus)
- ✅ Alkalinity increaser (Alka-Plus)
- ✅ Your chosen disinfectant (chlorine, bromine, active oxygen – or salt electrolysis system)
- ✅ Product for shock treatment (chlorine granules or oxidizing agent)
- ✅ Filter cleaner
- ✅ For hard water: Hardness stabilizer
- ✅ Optional: Pipe cleaner (for water changes)
Step 3: Establish your routine
Choose a fixed day of the week. Sunday. Wednesday. It doesn't matter.
The main thing is: it's always the same day.
Add it to your calendar: "Hot Tub Pampering - 10 Minutes".
And then: Stick to it. Every week. Without exception.
After 4-6 weeks, it's no longer a chore. It's simply part of your routine.
Like brushing your teeth. Like doing the weekly grocery shopping. Like filling up the car.
You are not alone
If you are unsure at any point – whether in choosing the right method, in initially setting the water balance, or in the case of a persistent water problem:
You don't have to figure this out alone.
That's exactly what I'm here for.
Over the past few years, I have advised hundreds of hot tub owners – from choosing the right model to the optimal water care routine.
And I learned one thing:
The best hot tub owners are not the ones who get everything perfect right away.
The best hot tub owners are those who ask for help when they need it.
Their offer: A personal consultation
If you wish, we can meet – by phone, video call or in person – and I can help you:
✅ Finding the right disinfection method for your hot tub and your situation
✅ Adjust your water correctly the first time (pH value, alkalinity, disinfection)
✅ Establishing a routine that fits your everyday life
✅ To solve a persistent water problem that you have been struggling with for a long time
The conversation will cost you nothing.
No sales pitch. No hidden costs. Just a conversation between someone seeking help and someone happy to help.
Why?
Because I want you to love your hot tub. Not just in the first few weeks when everything is new and exciting. But also after a year. After five years. After ten years.
And because I know:
Good water care is the foundation for this.
➡️ Book a free hot tub consultation
And then we'll work together to make your hot tub what it should be:
Your personal wellness retreat. Every day. Without a second thought. No ifs, ands, or buts.
One last thought
A few years ago, a customer stood in front of my office.
He had bought a hot tub six months ago. An expensive model. Beautiful garden. Perfect conditions.
But he didn't use it.
"Too complicated," he said. "Constant problems with the water. Cloudy, smelly, slippery walls. I'm fed up with dealing with it."
We sat down together for an hour.
I showed him: the pH level was 8.2. Disinfectant was far too low. The filter hadn't been cleaned for three months. No shock treatment, no water change.
No wonder nothing worked.
We changed the water, explained the basics, and established a routine.
Three months later I received a message:
"Now I understand why people rave about it. I use the hot tub every morning. Best investment of my life."
The hot tub hadn't changed.
Just the water. And the routine.
The same thing can happen to you.
They have the knowledge. They have the tools. They have the instructions.
Now it's entirely up to you.
Good luck – and above all: Enjoy your hot tub!
P.S.: If you found this guide helpful, feel free to share it with other hot tub owners. The more people understand how easy good water care can be, the fewer frustrated hot tub owners there will be. And that would be a shame – because a hot tub is too beautiful to sit unused in the garden.
