Poolrite s6000 titan pool filter

SOURCE: Sun damaged pool noodles causing pump problems.

you just need to clean the filter. What kind of pool/pump do you have? If it has a cartridge filter it should be easy to take apart and spray off with a water hose.

SOURCE: my pool pump pumps water, return is low pressure

fix any air leaks on suction side of pump. Check valve positions.
Clean filters...may need to replace cartridges in cartridge filter, or take out D.E. grid assembly and clean it on a D.E. filter, or change sand in a sand filter...

SOURCE: my pool sand filter pump isnt filtering the water

could possbly be a bad gasket on the vari-flow valve. When is the last time you backwashed?

SOURCE: air in filter on hayward above ground pool.

This is common the first 30-60 seconds after turning the filter on. The filter is purging its self of the air, sometimes algae or small debris will shoot back into the pool as well.

If it is constantly getting air then replace your o-ring on the that clear cover (Strainer Cover) make sure you use a lubricant, and like djtc66 said re-wrap all threaded areas with teflon tape.