OK, I've got an idea of what you're dealing with, but if I'm right the problem will be with you for awhile.

Do ALL of these things:

1. Complete both the pool equipment and pool test results as fully as you can. (I could ask all the ?'s, but this is easier for both of us.)
http://pool9.net/pf-equip-form/ -- http://pool9.net/pf-hist-form/ (Thread # 24809)

2. Open your filter OR backwash, and tell me what COLOR the goo on the cartridge, or the discharge from the filter is.

3. Take a look INSIDE the back of a china toilet (not: old cast iron!) in your house, and tell me what colors you see.

. . . meanwhile, keep your chlorine in the dark yellow range.

. . . membership upgraded.