ph and chlorine problems

[bassfam]

I have an 18,000 gallon in ground vinyl pool. I am having some problems. I have a hard time keeping chlorine in the pool, and cannot keep the pH high enough. The chlorine is currently at .5 or so, the pH is at 6.8, and the alkalinity is at 150. These levels never change, no matter what we put in the pool. Well they change for about an hour, and then everything goes back down to these levels again. The water is very clear, but there is constantly a film on the walls of the pool, and on the bottom. It is not algae, but everytime I vacuum it up, i backwash, but the film is there the very next day. WHAT DO I DO?
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[HoneyGrlone]

hey there bassfam,
Are you shocking your pool weekly? Do you keep chlorinator in the pool? As for the ph level, try using baking soda. It's the same thing that you buy at the dealers, but a lot cheaper. I use 2 1/2 pounds every other week to maintain my ph.

[Johnny]

Try using a solar cover if you don't use one now, that should help hold in the chlorine. If you do, how are you adding it?

As for pH, the baking soda is a good idea as stated above.

That film you're getting might be some alge, if your chlorine is low, you'll get alge for sure.