HI, we just bought this house with inground vinyl liner pool with DE filter. A friend came over to help us open it and give us a quick lesson, but we are struggling now. I've been reading through forums and I've ordered the real test kit - it's coming Monday. Right now our problem is that I tried to start vacuuming the pool this morning and very low suction. My husband checked the filter and he said the pressure is too low. He backwashed quickly, no improvement. He opened the filter and found all DE at bottom of filter. We haven't added any since initially opening pool 2 weeks ago now. Any ideas what the problem might be - where we look and how often we need to add DE and do we need to remove it from bottom of filter? Thank you so much!