We had a DE filter in our old house. My wife (prior to our marriage) used to just shut off the pump during the winter and let it turn green. When spring rolled around, I took charge and did the following; Shock the pool and run the filter. It clogged up after a few hours. Backwashed and did it again. After a couple of cycles, it got to about 12 hours between backwashes and then 24 hours. Took about a week to get the water nice and clear. Anyway, that's how I did it in 1983. We bought a different house that year which had a cartridge filter and.....never allowed the pool to get green over the winter againt.

Anyway, that's my story and I'm sticking to it.

Kevin