Maintaining the correct chemical levels

PH levels range from 0 to 14. Testing the water will indicate whether your water is acidic or alkaline.

A ph level of 7 or under tells us that the water is too acidic; this may cause swimmers to suffer from skin and eye irritations. It will also cause swimming pool finishes and any metal equipment to corrode.

A high ph level tells us that the water is alkaline. The water may become cloudy and scale may form similar to kettle elements.

By maintaintaining your ph levels in your spa or swimming pool at 7.2 - 7.6 will allow you to bathe in comfort and allow the best out of your chlorine sanitizer.

If your Ph level is too high it can be reduced by using PH reducer (known also as dry acid or sodium bisulphate).
If your ph level is too low you can use ph increaser (known also as alkali or soda ash).
Ph levels can be tested with a suitable test kit and by using phenol red test tablets.
Please note it is important that you add a little of these chemicals rather than one large amount. You can always add more but it will be harder to adjust if you have added too much!

Chlorine levels

Chlorine is the most common and effective sanitizer for use in spa and swimming pools. This is available in Liquid, tablet or granules.Chlorine will kill algae and bacteria oxidising organic matter. A well maintained spa or swimming pool should have no chlorine odour.

Free chlorine levels are tested by using a suitable test kit and DPD1 test tablets. Free chlorine is the amount of chlorine available in the pool once the demands of the water are met. It is the chlorine free to kill and attack any pollutants entering the spa or swimming pool.
The free chlorine level should ideally be 1.5 - 3.0 mg/l

Combined chlorine

After chlorine is added to the spa or swimming pool water,some of it reacts with any nitrogenous matter to form combined chlorine (chloramines). Chlorine can be the cause of strong chlorine odour and can be irriating to eyes and skin.

To test for combined chlorine you need to carry out a free chlorine test using a dpd no 1,then add a dpd no3 test tablet and subtract the dpd1 reading away from the total and the remaining figure will be the combined chlorine total.

The combined chlorine levels should be zero in an ideal situation, but should be kept as low as possible. - See more at: