I have a sand filter like the one I have attached a picture of. Over the last few weeks the pump has not been sucking as strong as it used to and the pump basket has had a lot of air in it. I have not seen any water leaks but the water drains out of all the pipes and salt water generator when the pump turns off. Tonight I was standing near the pump when it turned off and I heard a sucking sound like air was being sucked in somewhere from the white valve on top of the sand filter somewhere near the handle. Are there user replaceable washers or seals in the filter that I could replace myself or do I need a professional.