Well I had to get this filter last year due to my old sand going bad. I called around and looked around and this filter was suggested to be the best for my application, 24k IG Vinyl pool with a 3/4hp hayward pump. pluming off the pool is only 1 1/2 since it is and older pool and the new filter has 2". I took the filter apart this spring to clean only to find it just about filled with DE. I guess when I was back washing I wasn't back washing as much out as I thought I was. Basically the filter was just about half way filled up with DE. I had to dig it out before I could get my grids out. I took it all apart cleaned it all up and put it all back together the way it came apart. Started the pump up and filled it with 6lbs of DE per the filters requirements through the strainer. I didn't notice the DE coming back into the pool until I had to backwash and refill with DE the next time around, about a month later. Then when I add DE I can see the DE coming back into the pool in the return jets. From what I can gather my grids are bad, how they can be bad I don't know from what they looked like when I cleaned them, I don't see how they can go bad other than something physically cutting them or something to open them up enough to let the DE go through. Any thoughts?