Thank you pool doc!! Your the best.....

[PoolDoc]

It took me a long time to go through this thread.

1. Remove the sand filter.
2. Run the pump ONLY on low speed.
3. Add chlorine ONLY in the evening. Brush the pool after adding chlorine.
4. Don't add ANY thing else UNLESS you need to add borax to raise the pH or acid to lower it: if the pH is between 7 and 8, leave it alone.
5. EITHER add DE to test your filter OR get a new Unicel.
6. Do NOT clean the filter unless you are seeing at least a 3# increase on low speed.
6. Report AM FC and CC AND filter pressure 1x per day; no other reports.

I really wish you'd get a new cartridge, if you can. Do the DE or a new Unicel -- MUST have Unicel name on packaging! I'm finding many, many cartridges are NOT what they are sold as.

Also, the next time you clean the cartridge, please photograph it -- outside, inside tube, caps.

Good luck!