Question on pentair sand filter plumbing


New member
Mar 13, 2021
Hello, I was in the process today if disassembling my sand filter housing for the first time in order to change some orings and swap out the sand. The main pvc line going down from the 6 way valve to the laterals was extremely tight on the valve side joint/connection. After working it out I noticed it is extremely rough, pitted, gouged etc. Is this normal or should that connection be clean and disconnect relatively easily? It was so tight that it would not disconnect with the lateral lines remaining in the filter housing, instead it pulled them up out of the sand. Pictures attached. Any advice would be appreciated.

Thanks in advance


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Mod Squad
LifeTime Supporter
Jul 10, 2012
Tallahassee, FL
Mine just slides on and off. I wonder why yours is so tight? Is this the first time you have opened it? I say get some VERY fine sand paper and do some touching up to smooth it out to make it easier to get off and on. It being rough will not affect it's ability to filter your water. It just makes it harder to work on down the road.


Silver Supporter
In The Industry
Aug 15, 2017
Spring Valley, NY
Most likely the reason it was so tight was because sand got up there when it's not supposed to. That can happen either from it being filled with too much sand from the get go or by not waiting the proper time between the different valve positions and the pump was turned on too soon while there was still turbulence say from a backwash. Have seen this also when someone forgets to shut the pump off before moving the mpv from filter to backwash. You pulled the white tube out of the sand as it seems then you'll need to remove all the sand and remove the laterals from the bottom, clean all sand that got into it, get all the sand out and re seat it and refill with new sand while you're at it. More sand isn't better but rather problematic. Do not overfill
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