DE returning to pool - any suggestions?

[atterbud]

Hi
I live in Connecticut and I have a 30,000 gallon vinyl liner IG pool with Hayward 1 1/2HP Super Pump and DE4820 DE filter and a 7 way multivalve. The pool is 5 years old. We noticed that DE was returning to the pool this year after opening and cleaning the pool. I have taken out the DE filter grids and taken each grid out and cleaned it thoroughly and see no tears in the fabric. I have also replaced the rubber o-ring on the return pipe that the grid housing slips onto. I did find about 20-30 acorns in the filter housing and figure a squirrel must have put them in the housing over the winter as I left the drain plug out.

Unfortunately, we still seem to be getting DE flowing back into the pool. You cannot see it in the returned water and the water is not cloudy, but after having the pump on for a few hours you can see the DE across the bottom on the pool.

I wonder if anyone else can make any suggestions. I wondered if the multivalve may be damaged or perhaps the gasket needs to be replaced? Or maybe I have missed a tear. I assume that as the DE is not pouring out in great volume, a very small tear could exist somewhere that I have missed.

Any help you can would would be appreciated. Thanks.
Regards,
Dave.