About a year ago I added a quantity of 20 Mule Team Borax per pool math to my pool to raise my borates level to 50 ppm. I test the borates level with Lamotte test strips and get a reading between 50 and 80 parts per million. When i input a reading of 50 ppm borates in the pool calculator to arrive at the quantity of acid I need to reach my target ph level I get a result that is way too high resulting in lowering my ph to a level lower than my target level. I tried doing the Taylor acid demand test and the result of acid demand is much lower than what pool math suggests for borates of 50 ppm. When I play with the numbers in pool math it suggests that my borate levels are really 15 ppm based on the Taylor acid demand test.
Has anyone encountered this problem before?
Should I assume that the Lamotte test is not accurate and that in the last year my borate level has decreased by 35 ppm? Do borates get used up in the pool over time?