Check valves?


LifeTime Supporter
Feb 26, 2010
Guam, USA
OK, this may be a dumb question, but my sand filter drains all the water into the pool every time I shut the pump off. Should I add a check valve to the plumbing and where should I put it? I thought it was a problem with the multiport valve for the filter, but I opened it up, and there is nothing wrong in there. Is it normal for the filter to drain when the pump shuts off?


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
When the filter drains down every time the pump turns off it means you have a leak in the plumbing somewhere. You need to locate and fix the leak.

Adding a check valve would somewhat mitigate the problem, but it would also slightly reduce the efficiency of your system. It is much better to find the leak and not bother with the check valve.

The leak could be almost anywhere. The first place to look is the lid of the pump strainer basket. Make sure the o-ring is in good shape and the lid is sealing properly. After that you need to look for places water is spraying out when the pump is running.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
You have an air leak.....most likely on the suction side. Once you find that leak (it'll take some detective work) your filter will not drain.

EDIT: ditto what Jason already posted

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