Normal pressure rise rate for a sand filter

[glemerick]

How long does it take for pressure to rise 25% under normal filter operations (assuming the pump runs 24 hrs per day) & a clean, healthy pool water condition? My sand filter pressure gauge appears to work (it drops to zero when the pump shuts off). My normal operating pressure after backwash is 11psi. I can go several weeks & it never seems to rise much at all.


I read here that I should back wash when the pressure goes 25% above the clean/start point but mine never seems to rise much off the clean point. The filter & the sand are pretty new, it was changed out last year. I gave up relying on the pressure gage to tell me when I should backwash it and have been in the habit of backwashing it monthly. I can easily imagine it would take months to get a 25% rise. What is typical for you?

Thanks,
Greg

 

[Divin Dave]

Hi Greg,
Yea, the factors that you mentioned, it can take months for the pressure to rise 25%.
Another big factor is how large the filter is. The larger the filter, the slower the pressure rise will be.

Even though I have a cartridge filter (a big one), I only have to clean it once a year.

 

[Cedarpool]

I swapped out my existing check valve with a FlowVis (easy DIY job). I find it is much more effective to monitor the drop in flow rate than to rely on the pressure gauge. I have a Pentair sand filter and they recommend backwashing when the flow rate GPM drops by 30% below the clean rate. I get several months between backwashes.

 

[RandyM27]

My sand filter doesn’t generally have a pressure rise during normal operation. It’s really only in the spring with a lot of pollen in the pool or after vacuuming and picking up fine debris that I have to backwash.

 

[glemerick]

Thanks everyone! Appreciate the calibration on typical pressure rise rates. I was starting to wonder if mine was normal. Sounds like it is.
Greg