Quote Originally Posted by mshumack View Post
I am leaning toward believing Ben's kit because I also find I have no chlorine after the pool sits all night. But I have about 5ppm Chlorine while the pump (and SWG) are operating. Sounds like low CYA doesn't it? I should be able to maintain chlorine overnight - right?
Actually if you are losing the chlorine at night - that would not be due to CYA - CYA protects against sunlight - and there is no sunlight at night. Sounds like you have organics in the pool using up chlorine at night.

As far as which to believe - I have the same problem as you - Ben's kit tests <20, and pool store tests at 40. I think it might be user error on my part. Are you testing in a brighter/lighter area than you were before?