Re: PH keeps rising
Higher TA will help keep pH from dropping when using stabilized chlorine but if pH is still rising then you have to find the source. Higher TA actually causes pH to tend to rise because of increased outgassing of CO2. Outgassing of CO2 is a main cause of pH rise in pool and aeration (from fountains, negative edges, water features, etc) increase aeration and therefore pH rise. Also, the lower the pH the faster it rises. TA is basically a measure of the amount of bicarbonate in the pool water which is in equilibrium with carbonic acid and this is our buffer. Carbonic acid is basically CO2 dissoved in water (think seltzer). The higher the TA the higher the bicarbonate and therefore the higher the carbonic acid (to keep the equilibrium). The lower the pH the more bicarbonate is converted to carbonic acid (carbon dioxide in the water). The more the aeration the faster the CO2 gasses off (think shaking the bottle of seltzer to make it go flat). The BIODEX products are mystery products, no one knows what is in them and if I don't know what something is I do not put it in my pool.
Bottom line is this. IF your pH is rising and you don't know why lowering the TA often helps. Not dropping the pH below about 7.6 often helps. Adding borate to 50 ppm definitely helps.
Retired pool store and commercial pool maintenance guy.
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