Waste, thanks for your continued help...

1. It's a Hayward DE-3600. 36 Square foot grids.

2. I turn off the pump. I hook up the backwash hose. I put the multi-port on backwash for at least 3-4 minutes. Typically, I will wait 1-2 minutes after the little jar on the valve is clear. I turn off the pump. Set the pump to rinse for a minute. Turn off the pump. Set the pump to filter. Add 4.5 lbs of DE through the skimmer.

**I haven't been using the whole 4.5 yet as it was stopping flow. I have been using about half of that does before the pressure builds.

I hope this helps you to help me and hopefully solve the mystery. Right now the pool is clear as anything so something good is happening. There was a lot of dirt (debris) on the bottom not that it was clear and I vacumed that out to waste today which cleared it up even more.

3. No DE is coming back into the pool through the return jets.