De entering return line when pump comes on


Feb 6, 2018
Los Angeles, CA
I have a pentair quad de filter, brand new. I’m getting de coming in the return line briefly when the pump first turns on. It’s a small amount but noticeable. Clouds the water just a touch briefly. This last about 5-10 secs and then it’s fine. What could be cause this, any ideas?


Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
Franklin, NC
My first guess (and it's just that, a guess - I've never had a DE filter) is that one of the grids is not seated properly. On start up a little DE gets past, but pressure forces the filter grid closed as long as the pump is running. Turn off the pump, pressure drops and misalignment reappears.

It will not hurt my feelings if I'm wrong or someone makes fun of me.....