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Pool Chemistry 101-C: Caring for Your Water

Updated: Feb 26

Good water care is an ongoing process requiring multiple aspects to be correct, monitored, and maintained. The first stage of caring for your swimming pool, spa, or hot tub water (hopefully) occurred at manufacture/installation – the specification of the correct pipework, flow fittings, filter, and pump. Following that it is important that all these things are maintained in line with the required schedule. This schedule may have a standard recommendation, but as all water systems are in some way unique, it is often up to the user – with advice from their installer – to decide when to change or

clean/backwash their filter or carry out other

necessary tasks such as cleaning of the pool

or spa itself.

The next stage is “disciplined use” of your bathing water. Generally, this is the advice you may hear or read about avoiding cosmetics, detergents, and other contaminants (no peeing in the pool!), plus other measures such as showering before use.

There are many other factors that can affect the quality of your water, but possibly the largest and most important factor is how you, the user, adequately maintain your water balance before, after, and between uses.

This maintenance process is what we call The Water Care Cycle.

The Water Care Cycle can be simplified into the three key stages shown below and these actions are a constant necessity to ensure that your water remains clean, safe, and that the water balance – or chemistry – is kept within the correct ranges for each measurement.


Testing your water is vital to ensuring it remains clean and healthy. We recommend that you use a good quality, reliable water test kit – the best that you can afford. Many people will use “test strips” because they are cheap, easily available, and easy to use. However, they can be unreliable, easily misused or misread, and are not (in our opinion) an accurate way to manage your water – some brands have very vague measurements.

In spas, hot tubs, and small pools that have had the filtration running for at least one cycle, a single test is usually sufficient. In average pools and larger we recommend taking 3 samples from different areas of the pool and using the average reading.

If you want to speak with us about upgrading what you test your water with, email enquiries@energiseleisure.co.uk or call us on 0333 577 9692.


Once you have your results, the next step is to carefully assess them – be as accurate as you possibly can when reading test strips or visual kits and make sure you follow the manufacturer’s instructions. Some of the colours can be quite subtly different, so if in doubt retest or check your reading with someone else.

Once you have confirmed your test results, compare them to the recommended levels to decide if you need to add any chemicals to alter your levels.

If you have a result that looks really unusual (based on your experience of your water or suddenly far out of range) then do nothing until you’ve conducted more tests. It is better to take the time to confirm your results and make 100% sure before you move on to the next stage than it is to rush through and add chemicals that you might not need, which could risk making your water chemistry even worse.


Changes to your water chemistry should be made in this order:

  1. 1. Total Alkalinity

  2. 2. pH

  3. 3. Sanitiser (usually chlorine)

High alkalinity will make it difficult to adjust pH and low alkalinity could make it difficult to accurately adjust your pH, so start with that.

The pH of your water will affect how effective your chlorine is – we recommend a target value of pH 7.3 within a broader range of 7.2-7.4. Most recommendations from others will fall in the 7.2-7.8 range, but at higher pH values, Chlorine (if you are using it) is less effective.

Once you have those in the correct range, add your sanitiser if required and once the water has had opportunity to cycle through your filtration system make sure you retest pH and sanitiser levels and readjust again if necessary.


  • Always adjust your chemicals in the above order

  • For large pH adjustments (adjustments above 0.2) add 50% of what you think you need

>> Then retest and make further adjustments if necessary

>> It’s better to deliberately undershoot than accidentally overshoot

  • Always check and follow the instructions specific to your chemical brand

>>Usually available in a manual and/or on the label

If you have any questions or need help with your water care, send us a message on enquiries@energiseleisure.co.uk or speak to us on 0333 577 9692.

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