Help, chlorine disappears, ph drops

[DavidD]

Something seems to be consuming it. Not sure what it is but I'd try to keep it up around 15 for a couple of days more, maybe you'll win. The PH problem baffles me as well, especially since your using only bleach. Maybe we'll get lucky and the "Doc" will take a look.
As far as using the pucks to get your CYA up, that's an excellent idea except they will also lower your PH. You'd better keep a close eye on it if you go that route and keep plenty of borax on hand.

[waterbear]

How long ago did you open and was the CYA at opening as high as it was on closing? If not and you opened recently that could be the problem.

[doriec]

I ran the cya at 50 last year. Using Ben's test kit, the cya was still the same this spring. Dorie

[waterbear]

Well, at least that eliminate biodegration of CYA as your problem!