Have an old in ground concrete pool, late 1960 install. The last couple of years been having flow issues where suction water is poor. Last year replaced the filter and thought that would solve it and seemed to for a period. This year cleaned filter pre season and started with new batch of DE, yes DE filter. Worked good, then add Chlorine stabilizer and flow dropped and pressure at filter went up. Expected that as chlorine was absorbed into water and it did improve. So a couple of week slater backwashed and flow was good and pressure had dropped. Then a few weeks later flow to pump was down again, not fully filling pump tank, backwashed again and filled right up and had good flow. Then same issue a couple of weeks later. Since then just continues till now only takes a day or so for flow to drop. So tried running in recirculate only, flow comes right up and stays up. Then after running for a few hours switch back to filter flow is good, but again falls off over next 24 hours. Have notice that when I switch from filter to recirculate get a burst of air in return lines at pool, but just brief and kind of makes sense air in system due to low flow. Air in filter hasn't been real issue, just a very little. Pump is Pentair var-flow and about 10 years old, could impeller be bad? Have two suction lines, skimmer and pool drain/bottom. As you would expect flow is never that great through either, but when opened this year ran water back through both and flow seems good, just garden hose volume, and equal through both. Seems like I might have a small leak in a return link, but can't confirm at this point. All lines were replaced about 30 years ago, I have lived and had this pool since 1986 so know history. Used to have much better skimmer intake flow, but can't figure out what is going on. Now down to thinking pump impeller is only option, but why the declining performance rather than just constantly bad. Did replace the flow control valve with new filter also. Like I said the hydraulics of this just don't add up to me and I do have some knowledge of flor and pressure from cons't machinery experience.
Hoping someone has a perfect answer! If pump is next step would probably wait till closing, in Michigan, and do it then. Are there services that do it or can I do myself with basic mechanical knowledge.
Thanx.
Hoping someone has a perfect answer! If pump is next step would probably wait till closing, in Michigan, and do it then. Are there services that do it or can I do myself with basic mechanical knowledge.
Thanx.
