New here...just 2 quick questions.

My sand filter is making a noise...leaning in it comes from the water going back through the return pipe to the pool. the noise sounds like water is having a hard going through...not a good flow sound. What would cause this??????
I ordered a new gasket for my pump. Could it be the sand filter causing this....like replacing the O Ring. I noticed a small leak when I opened my pool yesterday.

Also, this year I noticed alot more algae/pollen floating in my pool. I skimmed it and being using panty hose in my skimmers. Shouldn't my filter pick that up????? I was just wondering if I needed new sand because it wasn't picking up? The sand is about 5-6 years old when we bought this house? Or should I just keep filtering and let it settle and vacuum it?

thanks!