We just bought this house and I have a pacfab ns-48 DE filter and my pressure kept going up to around 25-30 psi even after backwashing. So I pulled the top off to clean the grids and add new DE. The first thing I saw was huge(2-3 inch diameter) chunks of hard DE and under one of those chunks was the air vent strainer. It was completely caked and collapsed. On further inspection of the grids I found several broken, so I replaced all of them with new grids and a new strainer. Reinstalled everything and filled with the right amount of DE. It ran fine for about 3 days and the pressure went up to 25-30 psi again. Tried backwashing and it was good for a few hours and did it again. Pulled the lid and the new strainer was clogged with DE and collapsed again. What could be causing this? I have been searching the web and haven’t come up with much. Any help would be appreciated.