my sand filter normally runs at about 15-17 psi..i didn't have any leaves (had a leaf net this winter) but lots of silt..thin layer over whole bottom..i decided to brush it and stir it up as i'm hoping it will pick up most of it into the filter rather than having to vacuum so much..within 20 minutes, my filter pressure went up to 25 psi, then 30 psi before i decided i better backwash...did a quick 5 minute backwash 2 minutes rinse and it dropped to 16 psi. i only noticed the filter pressure because i noticed that my side skimmer wasn't sucking as much as it usually does from the pool..that's the effect of too high a pressure..my filter can take 60 psi max so no worries but..a real world example for you