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Pool pH problems - pH help

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Adjusting pool water pH

Assuming that the total alkalinity level is correct, we adjust the pH according to the results of the pH test. Most better test kits have an acid demand test, which allows you to calculate the amount of acid to add in order to correct the pH. You generally need to know the volume of the pool to calculate the quantity required.

In general, the pH of pool water tends to rise. This is a result of chlorination, swimmer's wastes (sweat, urine, . . .) and nature's tendency to balance the pH of standing water at about 8.5 .

High pH can be reduced with an acid. The most common pool acids are:

  • liquid hydrochloric acid (muriatic acid) and
  • dry acid (sodium bisulphate).

Extreme care must be taken when adding acid to the pool, as negligence can result in serious burns. Before adding the acid, be sure there are no swimmers in the water and that the pump is running. You will need a plastic bucket to mix the acid in.

Always add acid to water; never add water to acid! 3/4 fill the bucket with water from the pool. Add the acid to the bucket and pour it slowly around the deep end of the pool. If you are adding a large quantity of acid, do it in stages - DON'T add large amounts of acid to the pool at one time. Allow the pump to circulate the water for at least 4 hours and then test the pH again. A pH reading of 7.0-7.6 is required, with 7.2 being the ideal level.

If you add too much acid to the pool at one time, you risk etching the walls, corroding the pipes and pump fittings and you lower the total alkalinity of the water.

Low pH is increased with an alkali - this is most commonly soda ash (sodium carbonate). The amount of sodium carbonate required to raise the pH can be obtained from our soda ash calculator.

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