Help, chlorine disappears, ph drops

I have been reading this forum for 3 years now and have learned so much. I am having a problem, though, that is kicking my rear! These are my readings using Ben's test kit:
CC .5
FC 2
Alk 110
hardness 230
temp 87
Ph 7.2
stablizier 50
pool size-27,000 gal.

Here is the problem. I can't keep chlorine in the pool. I have shocked it for 3 days now up to 15fc--I have used 15 gal of bleach in 2 days. I just checked it after dosing it AGAIN this morning, and I now have 2 FC this evening. Also, my ph has never wavered from 7.6. I have added 2 boxes of borax in the last 3 days to get it up from 7. 2. It keeps going back down. The water is crystal clear.
Any ideas? Thanks, Dorie

doriec,
A couple questions before I'd venture a guess:
Have you added anything else besides bleach to the pool in the last few days?
Have you double checked the CYA?

Dave

I added borax to get the ph up. I also checked the cya twice. Dorie

Have you just opened the pool and had this problem since opening or has the pool been operating normally and the problem just occurred? Something is creating a chlorine demand. The trick is to find out what. Is there anything dead in your pool or skimmer? Have there been children using the pool and could one of them had an 'accident' in the pool? Any info like this would be useful.

I opened with no problems. I do have many kids in the pool, though. They are my grandkids and friends, and believe me, they know they'd better use the bathroom.:) I did get a clear cover--big mistake--I wonder if the sun is eating the chlorine. I ordered an SWG and the instructions say to run the stablizer at 80. I am thinking about using stablilized pucks until I get the SWG in to get the stabilizer higher. I am still stumped about the drastic ph drops. I have never had a problem with that. Any suggestions? Thanks, Dorie

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.

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.

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

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