Why Does my Filter Run at a High Filter Pressure and Have Reduced Water Flow to the Pool?
A dirty filter can reduce water flow to your pool. When the filter pressure rises 8-10 PSI over the clean starting pressure, it is time to backwash or clean the filter.
Another possibility is algae in the pool- it may be clogging the filter, keeping the pressure high. The filter cannot kill algae.
If the problem is still not solved, you may have a blocked or plugged return line.