Hello, TFP users. I have a Pentair Quad DE 80 filter. I love it. I open it up and wash the grids with the garden hose 4 times per year. My pressure has always stayed around 10 PSI (when it reaches 20 you are supposed to clean the filter). 2 days ago, I decided to do a SLAM due to a little persistent green algae. So, before starting the SLAM I noticed my pressure was at 30 PSI! I brushed my pool, vacuumed it, then I opened up the filter and sprayed everything clean. I also opened my pumps and cleaned those, as well as soaking my Polaris bag in a solution of bleach and water. Put everything back together, added DE and my pressure is still reading 25 PSI. Any ideas? We do have very hard water coming out of the tap (300), but we have had a lot of rain this past spring (free water!). Plus, my pool is surrounded by limestone rock which I'm sure leaches calcium into my pool as the water spills over this rock. My calcium sits at 600 and I can't drain right now. I'm wondering if I need to open the filter again, and soak my cartridges in a solution of MA and water. Thanks for the help!