Phosphates Masking CYA Readings??

[waterbear]

I test a lot of water and have never seen or heard of phosphates masking a CYA test. I have experienced a temporary lowering of CYA when a lanthenum based phosphate remover is added to the pool in a large dose but it has not happened every time and the CYA results have returned to normal in a week or two. I have never seen this particular effect documented anywhere but it is something I have noticed in my testing and also in my own pool when I was experimenting with lanthenum based phosphate removers.

[squirrel49]

Well,

Had my water tested at another store. Measured 35ppm CYA (Which makes sense based on the previously added 6lbs stabilizer) and ~1000 ppb phosphates. They never heard of phosphates masking a CYA test either. Looks like the first store was full of B.S.

All I plan on doing now is adding another 6lbs stabilizer and enjoying the summer. Am not planning on doing anything else about the phosphates.

Pat.