Hi Vicki,
DE is Diatomaceous Earth, of course! Everyone knows that. (just kidding).

You can look up a better definition of DE on Wikipedia than I can give, but suffice to say it does the same thing your sand does, but better because it's a finer filter.

http://en.wikipedia.org/wiki/Diatomaceous_Earth

It also requires a bit more work as you have to flush out the old and replace with new on occassion, sometimes frequently when you're fighting algae. But the results are the clearest water you'll ever see.

And because it's a naturally occuring substance it's fairly safe. When I flush, or more appropriately "backwash", I just run it out onto the yard. Been doing that for a couple years now and there's no trace of it or any damage. The first rain washes it into the ground.

But you can get the benefits of it with a sand filter too by adding a small amount. As you probably read, you'll have to add more each time you backwash the filter but the stuff's pretty cheap.

Quote Originally Posted by VickiP View Post
Hi, Just saw Chucks post. What is DE??? I read the thread but not sure what it is. Also we did have the water tested and no iron but small amt of copper and after the metal out the copper was not even reading. Should we still use the DE?