Had a small fissure in the standpipe of my lateral assembly, so I had to swap out the assembly. While I had all the sand out, I decided to go ahead and put new sand in there. It’s never been changed since I’ve owned the pool and who knows if it was ever changed by the previous owner. I know the prevailing theory around here is that sand doesn’t really need to be changed out, but I did it for the heck of it. Anyhow, once I got everything replaced and put back together, I ran a backwash, and then ran the pump at high speed to purge air. I noted my new baseline PSI at 8.5, which is 0.5 PSI below my old baseline. I checked the pool and the plumbing periodically for a couple hours after that and everything was fine. PSI had increased to 9, no leaks, everything seemed normal. Finally, about 5 hours after starting everything back up, I was getting the grill started for dinner and noticed that the water in the pool seemed too still. I went down to the equipment pad and saw that my filter pressure was at 15; my returns were putting out much less pressure than usual...about as much as they do when I have the pump speed turned way down. I backwashed, and my PSI returned to normal. I just went back out again after cleaning the kitchen and the gauge is reading just under 14 (about 2-3 hours later). What gives? Is the new sand just catching a whole bunch of fine particulate that the old sand wasn’t? I’ll add that the Tiger Shark was doing it’s thing for a couple of hours late this afternoon. Could some of the fine sediment in the pool gotten stirred up and finally captured by the filter?