The strainer basket in the pool pump housing assembly collects large pieces of debris that were missed by the skimmer or were sucked in though the main drains. The pool pump strainer prevents debris from entering the pump assembly and clogging the impeller. To prevent the strainer from clogging and reducing the flow of water through the pool system, the pool pump strainer basket should be checked and cleared weekly
Next you will have to relieve the pressure that has built up in the pool pump and water line. Note the pressure on the pressure gauge. It will typically read between 15 - 20 psi. To relieve pressure turn the air relief valve on top of the filter counter clockwise. Water will spray out initially as you see the pressure on the pressure gauge go to 0 psi.
To open up the strainer, 1-turn the two knobs on top of the strainer lid counter-clockwise and 2- swivel the knobs down away from the lid. Note: Some pool pump strainer lids screw on instead of having knobs. In this cases twist the lid counter-clockwise to remove the lid off the top of the strainer.