Pool cloudiness problem. HELP

[Froggypool]

I have already posted about this, but cannot find it in the forum. A moderator answered and said to check my sand level. I changed my sand yesterday, and it has been running about 13 hours with no visible change.

My pool has been cloudy for 3 weeks. Ever since I opened it. I have a 5 year old AG 30 ft (20,000 gal) pool with a 1.5 hp Hayward pump. I have a 250 lb 18 in. Sand filter. I have been using the BBB method for 2 years. This year I cannot get the cloudiness to go away. I have been trying to keep the chlorine level at 15 ppm for the last 4 days to kill algae. Here are my numbers, they have been running pretty consistent for the past week or 2.

As of this morning:

FC 10 (just added 7 ppm this morning to boost)
CC 0.5
TA 150
Ph 7.4
Calc hardness 70
CYA 55

[Pappy]

First, test your filter with D.E. Slowly add 1/2 cup of D.E. to the skimmer while watching the return. If you see white or cloudy stuff coming back through the returns, you may hve a filter problem.

If you don't see stuff coming back, read this thread. http://pool9.net/de-test/

You may be able to get D.E. @ WalMart http://www.walmart.com/ip/HTH-D.E-Fi...10-lb/20434370 Description is correct, PICTURE is WRONG.