Sand filter problem help request

[edwardsjw2]

I have been having issues with my sandfilter I keep seeing debris in the clear check valve before my chlorinate pool is 18000 gallon fiberglass photos of sand filter equipment tag below

 

[edwardsjw2]

One more bit of data last year the sand filter pressure ran between 20 and 28 this year I can’t get it to build over 21 psi i backwash but the filter die t seem to be filtering

 

[1poolman1]

One more bit of data last year the sand filter pressure ran between 20 and 28 this year I can’t get it to build over 21 psi i backwash but the filter die t seem to be filtering

The higher the pressure the less the flow. You could have a slightly clogged impeller. What is the debris that you see? Or, is it just bubbles?

 

[edwardsjw2]

I fixed it it was an issue with my multiport valve sticking allowing a small amount of material and water to bybass the sand bed