Pool Filter PSI all over the place


Well-known member
Nov 9, 2015
Lawrence, KS
We have a brand new pool and I just noticed that the PSI seems to be all over the place depending on where I have the waterflow coming from, either Main Drain or Skimmer. Normal starting PSI is right at 25 and then needs backwashed at 35. If I set it to skimmer flow only, the PSI drops down to 22 PSI. If I move it to 50/50 for Main Drain/Skimmer, it goes to about 30. If I shut off skimmer completely, it goes to the normal PSI of 25. All of this is taking place after I just backwashed this weekend. I have checked the skimmer and everything is clean. The water level is about two inches from the top of the skimmer so no issues there. The pool is literally one week old and we have not had anything in the pool yet. My PB walked me through everything but this one has me stumped. Any thoughts?


Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
Tucson, AZ
Other than having pretty high pressures (but be a VERY large pump), that all seems normal. With both suction lines open, the head loss is lower and the pump can move more water raising the pressure.

NOTE: Do not wait for a 10psi rise to clean the filter. We recommend cleaning when the pressure rises 20-25% over the clean pressure. Just pick a valve position to do this check.

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Well-known member
May 30, 2015
The "normal" pressure is the pressure at any of those positions after a backwash. "Normal" filter pressure will change depending on how fast your pump is running and what features are turned on/off.