I have a question about adding DE to filter.


LifeTime Supporter
Mar 21, 2009
Lower West Michigan
From what I understand adding DE to a sand filter creates a small layer at the top of the sand and catches all the fine particles. That means it is also catching anything bigger. Is there anything left for the sand to do? It seems to me the ideal thing to do would be adding sand to the filter until get you above the laterals, thin layer of DE, and fill it the rest of the way with sand. That way the sand gets the big stuff the DE gets the little stuff. I am guessing the DE will stay put when you backwash or it wouldn’t stay put during normal filtering.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
I can't imagine that working but it sounds like a great experiment you could try. It might just work! Report back your results


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
I nominate you to be the experimenter.

My fear is that if the sand layer isn't deep enough that some of the DE will find its way through the sand bed and into the laterals and out into the pool.


LifeTime Supporter
Jul 11, 2010
It takes so little DE to start raising the pressure. I would keep a super-close eye on the gauge during any experiments.


TFP Expert
LifeTime Supporter
Jun 12, 2009
NW Ohio
Well, I certainly wouldn't stop you from trying, but DE does eventually "go bad". The diatoms trap particles quite effectively and eventually become overloaded and must be removed. That is why DE filters dump the DE when they backwash and new DE has to be added. My guess is that your DE layer will start to clog at some point and you won't be able to get the DE out if it is trapped between layers of sand.