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Hot Tub Care Guide

When you own and use your own hot tub it is essential to keep it clean and clear of bacteria for a safe and pleasant bathing experience. The basic elements that go into maintaining and balancing your hot tub water are sanitiser, pH adjusters and shock treatments. This page will guide you through everything you need to know.


Your hot tub will need to be treated with a Sanitiser to control and prevent bacteria growth. Bacteria can multiply rapidly in a hot environment, so you must maintain an appropriate sanitiser level to ensure any bacteria in the water is killed. There are two main sanitisers available to keep your hot tub clean and these are chlorine and bromine.

Option One – Chlorine

Chlorine is the most popular choice amongst hot tub users as it is the most cost effective and fast acting sanitiser available. Chlorine is available in granules or tablets.

CHLORINE Granules – Chlorine can be added by pre- diluting in a container of warm water. We suggest you add chlorine in small amounts to start (unless the level is very low), to prevent over dosing. Then leave the water for about two hours, before retesting. This will give time for the chlorine to work, so if the water is very dirty then all the chlorine will be used up, and you will have another low reading. If the water is properly balanced then a chlorine residual will remain, and no more need be added.

HINT: Add a sprinkle of chlorine each time you get out of your hot tub and it will be clean and ready for use next time you want a dip!

CHLORINE Tablets – You can also add chlorine by putting tablets in a floating dispenser. The benefit of this is that there is chlorine being dispensed constantly, however it does give less control than using granules. We suggest you start by adding three-four tablets and adjusting the dispenser flow as necessary. The dispenser base can be twisted to adjust the flow of water into the unit. Simply twist the base to allow water flow through one hole, two holes, three holes or four holes. There should always be tablets in the dispenser, so DO NOT leave them until they are completely depleted before replacing. Re-test the water again in approximately two hours to see if the level has been raised sufficiently.

HINT: For safety remove your floating dispenser when your spa is in use.

Option Two – Bromine

Bromine is an alternative sanitiser to chlorine. It is more expensive and slower acting which means it takes longer to show a reading when testing and can result in cloudy water. Benefits include having a slightly softer smell, being much more stable in higher water temperatures and it is able to regenerate unlike chlorine (meaning you can keep reactivating bromide salts using a shock, reducing your need to add sanitiser). To use bromine tablets, simply follow the same instructions as chlorine tablets (above). You can also boost bromine levels with bromine granules or by shocking with Non Chlorine Shock.

WARNING: Never add water to chemicals, always add chemicals to water!

How to check your Sanitiser level

To test your sanitiser level dip a test strip in the spa water about 12 inches/30cm under the water level, following the instructions on the test strip container, and compare the colour to the chart on the test strip bottle.

The amount of chemical in hot tubs is usually measured in PPM, which stands for Parts per Million. If you are a chlorine user, keep the chlorine level at between 3-5ppm. If you are a bromine user, try to keep your bromine level between 2-5ppm.

Every hot tub owner uses his / her hot tub differently, so it is impossible to say how much sanitiser is required. Therefore we recommend that you test your sanitiser and PH level as often as possible and adjust accordingly, but you may wish to reduce these checks to every few days if you find your water doesn’t need adjusting that often. However if your usage increases then return to daily checks.

HINT: Hold your test strip horizontally to avoid the colours running into each other!

PH Level


The term pH is a way of describing whether your water is acidic or alkaline. The pH scale works from 0-14 with 7 being neutral. Anything below 7 is classed as acidic, and anything above 7 is considered alkaline. You must keep your pH level within the range of 7.2 to 7.8, and ideally 7.2 to 7.4 or you may experience some of the following problems:

Common low pH problems:

  • Corrosion of components
  • Skin and eye irritation
  • Poor sanitiser efficiency (you keep adding more sanitiser)

Common high pH levels problems:

  • Scale build up
  • Cloudy water
  • Skin and eye irritation
  • Poor sanitiser efficiency (you keep adding more sanitiser)

If the pH level is incorrect you will have problems balancing your sanitiser level, so always adjust this prior to adding sanitiser (but never run the spa without sanitiser in the water). To test your pH level, dip a test strip in the spa water, following the instructions on the test strip container, and adjust accordingly by adding pH Minus or pH Plus.

HINT: Correct pH levels will stop scale build-up in your spa pipework and pumps

Shock Treatments

In addition to whichever sanitiser you choose to use, it is recommended to “shock” dose or oxidise your water every week with a non-chlorine shock treatment.

Shock dosing is required to do the following:

  1. Break down Chloramines – sanitiser reacts with bather pollutants such as perspiration or dead skin, and produces a less effective chemical compound called chloramines which needs to be broken down. Chloramines have a strong chlorine odour that is often mistaken for too much chlorine, and make the water appear cloudy.
  2. Kill bacteria – some bacteria can become resistant to your sanitiser, so the shock treatment will destroy any remaining bacteria.
  3. Remove organic compounds – people carry organic compounds on their skin, such as dead skin and oils. These can accumulate in the hot tub and cause cloudy water, but shock treatment will remove them.

HINT: A capful of Non Chlorine Shock a week will help keep your water clear!

What is Non Chlorine Shock and What Does it Do?

Non Chlorine Shock (Potassium monopersulfate) also known as MPS is a chemical that provides a lot of benefit to your hot tub water and maintenance routine but also a product that very few hot tubbers understand or have used. In this article, we aim to answer some of the key questions around this chemical including "What does Non Chlorine shock do?", "Does it replace Chlorine or Bromine?" and "How often should I use it?".

What is Non Chlorine Shock?

Non Chlorine Shock is a powerful, odourless oxidising agent, which essentially means it works to eliminate contaminants in hot tub water. Oxidation is different to sanitisation. Oxidation is the breaking down of the oils and organics in your water whereas sanitisation is the killing of bacteria. Sanitisation is performed by effective sanitisers like chlorine or bromine. Note that while sanitisers can also oxidise, their effectiveness in both actions is reduced so you tend to use lots more sanitiser to perform both. Oxidation is performed very effectively by Non Chlorine Shock (Potassium monopersulfate) and this is why it offers great benefits to your hot tub experience. Non Chlorine Shock works with all sanitisers but does not replace them as it is not a sanitiser!

What Are The Benefits of Using Non Chlorine Shock?

  1. Improved Sanitiser Efficiency. By using an effective oxidiser like Non Chlorine Shock alongside your sanitiser, you free up your sanitiser to do what it is good at - kill bacteria! This results in less sanitiser being used in your hot tub.
  2. Fast and effective removal of oils and more. Non Chlorine Shock will oxidise oils such as body oils, lotions, deodorant, dead skin cells, sweat, detergents or leaves from your hot tub water, helping to prevent or reduce foaming and to reduce strain on your hot tub filters. This can also reduce reliance on chemicals that should be used sparingly such as Anti-Foam.
  3. Help water clarity. For many of the reasons outlined in point 2, Non Chlorine Shock can help improve water clarity fast. If you have milky or cloudy hot tub water but your chlorine levels, PH and alkalinity are ok then Non Chlorine Shock will oxidise the products causing this and help restore your water to crystal clear.
  4. Reduce the need to super chlorinate. Super chlorination is a good way to oxidise but by raising the chlorine level super high, you are risking bleaching and will potentially make the hot tub unusable for a period of time due to the strong smell/high chlorine level.
  5. Break down Chloramines. Sanitiser reacts with bather pollutants such as perspiration or dead skin, and produces a less effective chemical compound called chloramines (used up chlorine) which needs to be broken down. Chloramines have a strong chlorine odour that is often mistaken for too much chlorine, they can make the water appear cloudy and also sting your eyes. Non Chlorine Shock will effectivley oxidise this used up chlorine from the water, improving your bathing experience massivley.
  6. Re-generating spent bromine. Unlike Chlorine which turns into Chloramines once spent, Bromine can be regenerated. Using Non Chlorine Shock in a hot tub running on Bromine will oxidise the bromide ions (spent bromine) and form new bromine, this boosts the bromine level.

When and How To Use Non Chlorine Shock

Non Chlorine Shock is a powder that comes in many forms which we will outline below. We recommend adding Non Chlorine Shock weekly alongside your existing hot tub maintenance routine but in some situations such as severe foaming or cloudy water, extra dosing may be required. You can click through to each individual product below to see specific directions for use.

  • Non Chlorine Shock Pots- The cheapest way to buy the product is in simple containers.
  • Non Chlorine Shock Sachets - A convenient way to dose your hot tub with Non Chlorine Shock. Simply cut open a sachet and empty into your hot tub.

What is Total Alkalinity?

Total alkalinity (TA) is the measure of the capacity of water to neutralise acids. It is different to PH. It is measured by parts per million rather than a scale like PH. Alkalinity is important as it acts as a buffer when balancing PH. If your alkalinity is out, then it will be very hard to balance your PH level. In fact it is a good idea to balance your Alkalinity before doing anything else as this may allow your PH to fall into line too and will make balancing PH much easier.

What is PH and Why is it Important?

So once you have balanced your TA, the next step is to use a test strip to check your PH level. PH is the measure of how acidic or how alkaline your water is. 7 is the neutral PH level but in your hot tub you want to aim to get your PH between 7.2 and 7.8. If you do not do this you may in for some nasty and potentially costly surprises!

Potential Issues with Low PH:

  • Poor Sanitiser Efficiency. Using lots of chlorine to not much effect and adding risk to bathers.
  • Corrosion of hot tub components due to the acidic nature of the water.
  • Itchy dry skin and eye sting.

Potential Issues with High PH:

  • Poor Sanitiser Efficiency. Using lots of chlorine to not much effect and adding risk to bathers.
  • Scale build-up on the spa surface and on components.
  • Cloudy or dull water and foaming!

How to Balance PH & Alkalinity

Balancing your PH and Alkalinity follows the same concept for both. If your levels are low, add increaser, if your levels are high, add reducer! The only difference is what chemicals you need to use.

Lowering PH & Alkalinity Levels

If your PH and/or Alkalinity is high, you need to add a PH Minus to reduce these levels.

  • Do this gradually. Add the correct dose of PH Reducer, then run the jets and re-test in an hour or so and see if you need to reduce further.
  • PH Minus is the sole chemical used to reduce PH and Total Alkalinity in your hot tub.

Raising PH Level

If your PH is low, you need to add a PH Plus to increase these levels.

  • Do this gradually. Add the correct dose of PH Increaser, then run the jets and re-test in an hour or so and see if you need to reduce further.
  • PH Plus will increase your Alkalinity level slightly too so keep an eye on this as remember Total Alkalinity is the buffer to allow your PH to be set.

Raising Total Alkalinity Levels

If your TA is low, it is most effective to use TA Plus to increase this level. PH Plus will increase your TA as mentioned above, but it will do so at a slower rate.

  • As with all other adjustments, remember to do this gradually so that you don’t increase TA levels too high resulting in the need to bring these down again.

Does the balancing ever end?

Generally speaking, once your levels are set they should stay roughly within range however lots of factors impact this including other chemicals added to your hot tub, bathers, air injection into your jets and more!

Common FAQ’s

I use Chlorine Tablets (Trichlor), why is my PH always low?

This is a very common question and the answer is quite simple, Trichlor Chlorine Tablets are acidic by nature and therefore as they sit in your dispenser or filter, they are constantly lowering your PH. We recommend Chlorine Granules as a default sanitiser as it is more PH neutral and prevents this issue. Bromine is also more PH neutral than Chlorine Tablets.

Whatever I do, I cannot get my PH correct - help!

Firstly, check your alkalinity. If your PH is hard to set, then TA may be causing the difficulties in setting your PH. Secondly, how old is your water? If your water is 3-4 months old, it is probably due a water change as the TDS (Total Dissolved Solids) have got too high. TDS is the measure how much ‘dissolved stuff’ is in your water; this includes all chemicals you add and anything taken into the hot tub by bathers. Once this reaches a point, you will find it very hard to get your sanitiser or PH/TA levels right. It may also be worth checking the expiry date/quality of your test kit.

Does PH Plus, Minus and TA Plus Vary in Quality?

The chemical formula of these products is quite basic but we have seen some poor quality batches on the market in the past. These are generally weaker and therefore you use a lot more to balance your levels.

Does PH Plus or Minus have an expiry date?

The answer to this is the same for all chemicals. While we don’t really recommend digging out some 15-year-old PH Plus or Minus to use in your hot tub, if it has been stored in a cool dry place and hasn’t caked badly, then it is likely to be absolutely fine to use.

Water Changing

Water can only be chemically maintained for so long before excess build-up occurs and it needs replacing.

We recommend changing your water ever three-four months depending on usage. We suggest that you use a Hot Tub Flush prior to emptying the hot tub. This will remove any dirt/debris and loosen any calcium from the pipe work, which will then be washed away with the drained water. Before you refill your tub, we recommend using Spa Surface Cleaner to clean the spa shell.

Filter Care

What do the filters do?

The surface of the water is skimmed into the filter box, and through filter cartridges to remove dirt and debris.

How often should I clean my filters?

This will depend on your usage, but we recommend you clean them at least once every fortnight. Heavy usage such as parties will mean your filters clog up quicker. However the situation is different when you fill your spa for the first time, or whenever you drain and refill your spa. In this instance the filters may clog up within three–four days because of the small particles contained in tap water and any particles from manufacturing/transport.

What will happen if I don’t clean my filters regularly enough?

It is VERY important that the filters are cleaned regularly otherwise the water flow will be restricted and the spa will automatically shut down. The following diagnostic messages may appear on your touch pad if your filters are dirty; FLO, Heater Dry, LF, DR, OHH, or -- (two lines).

To confirm that the filters are the cause of the problem, remove them and run the spa for a few minutes to see if the message clears. If the message still does not clear, then try switching the spa off whilst the filters are removed, and then back on again. Please note that you MUST NOT run the spa for long periods without filters. If the message still appears after trying these measures, then please call 02380 812769 for further advice.

How do I clean my filters?

The best way to clean them is using our hot tub filter cleaner do this, spray the filter evenly with the instant filter cleaner, wait 15 minutes then rinse the filter with a hose.

Another way to clean your filters is to soak them in a bucket overnight with a Filter Cleaner solution. This solution breaks down oils from the pleats and gives the filter a deep clean. With both of these techniques, it is recommended

to allow the filter to dry as this resets the fibres in the filter media, making filtration more effective when the filter is put back into your hot tub.

You MUST NOT run the spa for long periods without the filters, so fit a spare set immediately when you remove the existing ones for cleaning.

HINT: Put your spare filters in and let the cleaned ones dry before using.

Other Water Products

What other products might I need to keep my tub in premium condition?

No Foam – Available as a liquid or a spray. This product will reduce the tendency of the spa water to foam, but it will not always stop it entirely. Foam is created as a reaction to natural oils in our skin, as well as contaminants such as remnants of detergents in swimwear, cosmetics and deodorants, etc. Showering with your swimwear on before entering the water will help reduce foam.

Spa Sparkle – This will help clear cloudy water and make your water sparkle. It is a coagulant, which means it will gather small particles in the water together so they are caught in the filters.

No Scale – This product is needed in hard water areas to prevent the calcium build up to form scale on the spa equipment and fittings

10 x Most Common Hot Tub Water Issues

1. Cloudy Water

Probable Cause:

  • Dirty filters
  • Excessive oils or organic matter
  • Improper sanitizing
  • Suspended particles or organic matter
  • Overused or old water


  • Clean filters with FreshWater InstantFilter Cleaner or FreshWater Filter Cleaner ®
  • Shock spa with sanitizer
  • Add sanitizer
  • Adjust pH and/or alkalinity with FreshWater pH/Alkalinity Up or FreshWater Alkalinity Down
  • Run jet pump(s) and clean filters with FreshWater InstantFilter Cleaner or FreshWater Filter Cleaner
  • Drain, clean and refill the spa

2. Water Odor

Probable Cause:

  • Excessive organics in water
  • Improper sanitization
  • Low pH


  • Shock spa with sanitizer
  • Add sanitizer
  • Adjust pH with FreshWater pH/Alkalinity Up to recommended range
  • Drain, clean and refill the spa

3. Chlorine Odor

Probable Cause:

  • Chloramine level too high
  • Low pH


  • Shock spa with sanitizer
  • Adjust pH with FreshWater pH/Alkalinity Up to recommended range

4. Musty Odor

Probable Cause:

  • Bacteria or algae growth


  • Shock spa with sanitizer
  • If the problem is visible or persistent, drain, clean and refill the spa

5. Organic Buildup/Scum Ring Around Spa

Probable Cause:

  • Buildup of oils and dirt


  • Wipe off scum with clean rag
  • If severe, drain the spa, use FreshWater Spa Shine after cleaning to protect the spa shell, and refill the spa

6. Algae Growth

Probable Cause:

  • High pH
  • Low sanitizer lever


  • Shock spa with sanitizer
  • Adjust pH with FreshWater pH/Alkalinity Down to recommended range
  • Shock spa with sanitizer, and maintain sanitizer level

7. Eye Irritation

Probable Cause:

  • Low pH
  • Low sanitizer lever


  • Adjust pH with FreshWater pH/Alkalinity Up
  • Shock spa with sanitizer, and maintain sanitizer level

8. Skin Irritation/Rash

Probable Cause:

  • Unsanitary water
  • Free chlorine level above 5 ppm


  • Shock spa with sanitizer and maintain sanitizer level
  • Allow free chlorine level to drop below 5 ppm before spa use

9. Stains

Probable Cause:

  • Total alkalinity and/or pH too low
  • High iron or copper in source water


  • Adjust total alkalinity and/or pH with FreshWater pH/Alkalinity Up
  • Use FreshWater Stain & Scale to inhibit metals

10. Scale

Probable Cause:

  • Total alkalinity and/or pH too high
  • High calcium content in water


  • Adjust total alkalinity and pH with FreshWater pH/Alkalinity Down
  • If scale requires removal, drain the spa, scrub off the scale, clean spa shell with FreshWater Spa Shine, and refill the spa
  • Add FreshWater Stain & Scale and balance the water using FreshWater pH/Alkalinity Up or Freshwater pH/Alkalinity Down