Lowering pH with CO2

[chem geek]

The answer depends on your starting and ending pH and on your TA level, but for going from 7.5 to 7.3 with a TA of 100 (and CYA of 30 and no Borates), it would take introducing 3.1 moles (about 136 grams or 4.8 ounces weight; at standard temperature and pressure, this is about 76 liters or 20 gallons of CO2 gas) of carbon dioxide to be added to a 10,000 gallon pool, fully dissolving into it (i.e. not just bubbling right out again). By the way, just as outgassing of CO2 increases pH with no change in TA, adding CO2 to your pool lowers pH with no change in TA as well.

Why do you ask? What source of CO2 do you have?

Richard