Quote Originally Posted by mjones
Can you add DE to a sand filter? I don't know what DE is, but I have seen it in the stores.
Yes. Both Poconos and I have been doing it for a while now. DE stands for Diotomaceous Earth. It's a fine white powder that is the key filtering component for DE filters.

You can add about a cup to a sand filter through the skimmer. Just add enough to increase the pressure about 1 lb. A cup should do it. It takes about 20 minutes for the pressure to rise. Don't add too much or you'll have to backwash immediately! Everytime you backwash, you'll have to add more DE. The best news about DE in sand filters is that it is CHEAP! I get a 10 or 15 lb box for about $8 and it lasts the entire summer, and improves my filtering nicely. It's one of the cheapest improvements you can make to a sand filter. The other is skimmer socks, which are about $5 a pack (they, of course, work on all filters).