about adding DE to a sand filter


In The Industry
Jun 11, 2010
Vernon BC
ok, i actually had to call around this town and find someone that actually could order me DE, no one stocks it.....anyways, for fun, since the guy on the other line sounded like "what **** does this guy want with DE, is he crazy?", i thought i would have fun with him and ask him about adding DE to sand filters. He brought up a valid concern, DE is not uniform in size, particles can range from 1 micron to 1 millimetre according to wiki and a sand filter would not be able to pick up the smaller ones, blowing it all over my pool. How would that affect; My pool? Health of the bathers, my kids? Would a floc agent help remove the smallest ones? and would I have to repeat that process each time i added it to my filter.

Help, i am starting to second guess my wish to use DE in my filter for an even cleaner pool.....your thoughts and comments would be much appreciated.


TFP Expert
LifeTime Supporter
Feb 23, 2008
Denton, TX
Some people report that the addition of DE has helped them clear a pool more quickly and others have reported not really being able to notice much difference. I am sure that there are many factors that contribute to whether one is successful or not when doing it.

DE and flocculents differ in the manner of how they work. DE aids in the filtration process by trapping the smaller particles in the filter due to the DE being porous and having sharp edges to "grab" things. Flocculents cause the particles to clump or agglutinate so they are easier to vacuum up or filter.

DE is unsafe when the dust is inhaled as it can cause lung irritation or damage much like silicosis. When it is wet or in the water, it is no longer able to be inhaled and presents no danger.


Well-known member
Jun 9, 2010
Pearl, MS
I used to add a little (about a cup) to my skimmer to "help" the sand filter out dead algae. It will make your pressure spike quickly as the sand bed becomes clogged. Keep a good watch on it. It does seem to help.


TFP Expert
LifeTime Supporter
Apr 8, 2007
Waaay NW MN
Also keep in mind that it will generally pass out of the filter when you backwash as well. I use it to "polish" my water after an algae bloom shock or just when we get a bunch of tree pollen in the pool


LifeTime Supporter
Feb 26, 2010
Guam, USA
I use DE in my sand filter every now and then. A little bit is all you need to really polish your water. HD sells the stuff, but only in a 25 pound box, so I've got plenty for the next 50 years or so :lol:


Well-known member
Jul 8, 2009
Merrimack, NH
To add to what's already been said above (for those thinking to do this):
Put only about 1/2 cup in a small container, fill with a bit of water, stir it up. Pour this milky concoction in skimmer. The important part is to wait 15 - 20 minutes, then check your pressure. About 1 psi increase is considered sufficient.
If you have a large filter, you may have to add more.
Some may like to do this after every backwash, but personally, I only do it a couple of times a season, as well.

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