I see a lot of posts saying CYA test over 100 ppm is not accurate. But what about after diluting pool water with well water that is 0 ppm CYA and then testing and double the result. Is that an accurate method? My kit has been testing right at 100, so I diluted with well water and I get the result of 50 ppm. Seems accurate, but am I wrong?
CYA Test not accurate over 100 ppm?
- Thread starter MT
- Start date
It does lose some accuracy by doing that....but not enough to matter in this case. I would still suggest you drain 1/2 the water to lower your CYA level, refill, then retest.
When doing the CYA test with 1 to 1 dilution the precision drops to +-30 (or worse), which is fine for estimating how much water replacement you need to do, but not good enough for much else.
Just because your water might really be at 100 ppm CYA, does not mean that another sample that was for example 140 ppm CYA would not also read 100 ppm CYA on the undiluted test. As this is more of an out of range condition than a true accuracy one.