I have been trying for years to understand how things work in my concrete pool .The pool is least 35 years old and since my husband past its been on going nightmare for me .So finally got things sorted out this year with pump and skimmers and what I need to do .But as the water is clearing up now I see the bottom I can see 2 of the return jets are staying closed with no water flow one is in deep end and the other in middle they stay closed all the time .The third one has no cover as it came off so I see water coming out of that .Skimmer seem to work well and I check them everyday and the pump is cleaned out . Anyway any solutions to this problem please .