Sand filter has me stumped..

[TMescan]

Hayward sand filter has worked great all year but now seemingly not filtering anymore. Usually upon backwash you would see the satisfying sight of all the debris washing away but now its just semi cloudy water for ~20secs and rinse produces the same result. The really abnormal thing is my filter pressure remains constant around ~15pi regardless of time ran or after backwash. Backwash and rinse pressure go to normal ranges when used and even let them run for a couple minutes with no change in filter mode psi. Sand and filter are new as of this year. Not sure what else to check from here and cant find any issues like this online any help would be great!

[Denniswiseman]

It seems like the filter is doing it's job
I only ever have had cloudy water in the backwash process
You dont normally get a load of debris because your skimmer basket and pump basket collects it all
What's the pool water clarity like?
Let's have your numbers (CYA is very important) Use a pool store if you don't have a FAS/DPD kit
FC:
TC:
pH:
TA:
CH:
CYA:

[Teapot1]

Initially filters drag out all sorts of dirt etc, as time goes on there is less dirt (hopefully) to remove so you see less in the backwash. From your statement that the pressure is 15PSI you have a powerful single speed pump and or small plumbing. So 15 pounds of pressure is pushing dirt through the filter media. I run at less than 0.5PSI saving a huge amount of electricity and money but still have fantastic clear water. As the filter captures more rather than pushing it through and back into the pool.
For backwashing I recommend using a piece of printed text under the viewing bulb so you can really see how clear the water is. Many people do not backwash for long enough not allowing the sand bed to expand sufficiently to release dirt deep in the sand. Overtime this builds up and silts up the filter. Domestic filters do not backwash very well.