CYA and pH

[iwannapool]

When adding CYA, say 50 ppm, how much will the water pH decrease?

[chem geek]

The answer depends on your TA level and starting pH, but assuming the TA is 100 ppm, your starting pH is 7.5 and you start with 0 ppm CYA, then adding 50 ppm CYA will lower the pH to 7.0 and will take 1.2 ounces weight of Borax for every 1 ounce weight of CYA to compensate the pH (i.e. to keep it at 7.5). It takes 67 ounces weight (4.2 pounds) of CYA to raise the CYA by 50 ppm in 10,000 gallons.

Richard