pH Problems

- getting the pH of the pool right is very important

It should be between 7.2 and 7.6 so clearly 7.4 is the ideal figure. if pH is either too high or too low it will cause any Chlorine sanitizer to be less effective, so you'll have to add more sanitizer to ensure destruction of all pathogens

This is an avoidable expense

pH remains too low

Likely cause: - This is usually due either to low pH of mains water (soft water areas), incorrect Total Alkalinity (TA) levels or to the use of low pH (acidic) Chlorine donors such as Triclhlor

Cure: -adjust TA as required

Correct the pH by adding pH-Plus powder

You might also consider changing to a high pH Chlorine donor to help to counteract the low pH of the fill-water

Dichlor is roughly pH neutral; Tricloro is low pH (acidic), while Calcium Hypochlorite and Sodium Hypochlorite are both high pH (alkaline) chlorine donors

pH is permanently too high

Likely causes: -

(1) High pH of mains water (hard water areas) or

(2) Regular use of alkaline chlorine donors such as Calcium Hypochlorite or Sodium Hypochlorite, or

(3) Hardness salts being leached from new concrete or mosaic pools

Cure: - in all of the above cases the solution is the same; correct the pH

For (1) and (2), consider a change to a low pH Chlorine source such as Trichlor to help achieve a balance between the high pH of the water and the low pH of the Chlorine donor

As for (3) - the difficulties with new pools will eventually clear up on their own accord over time

pH values are erratic and fluctuate

Likely cause: - The Total Alkalinity is too low to buffer the pH

Cure: - Add sodium bicarbonate to raise total alkalinity to 80-120 ppm

Dose at 1.5kg per 50m³ (13,000 US Gallons) of pool water; pre-dissolve and add via the skimmer with the pump on

pH is locked

Likely cause: - The water is over buffered due to high Total Alkalinity (TA) - this is a common problem in hard water areas

Cure: - Add dry acid (Sodium Bisulphate) to lower the TA to 80-120 ppm

The dose rate is 1kg per 50 cu metres of pool water

Add the acid, a little at a time and pre-dissolved at a dilution of 10:1, to the deepest part of the pool with the pump turned off

Leave the pump off for 24 hours, re-test and repeat as required

Note: It may take weeks of patient treatment to reduce TA to acceptable levels


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Ken Walker - MyPoolGuru©