Opened my pool and everything was working fine. Then at some point, my DE filter pressure gauge went to what looked like zero. I removed it, cleaned everything up and reinstalled but no luck - still reading zero. I figured I needed a new filter and ordered a nice glycerin filled one from Amazon LINK. I just installed it and it's reading 2 psi when it should be reading at least 10. I removed the pressure relief valve and cleaned it out, but still no luck. I installed the old gauge and same story. What's going on here? Everything seems fine other than the pressure gauge not reading what I expect. Filter is a Hayward DE-6000.