Should I change my filter sand?

[Watermom]

DE is Diatomaceous Earth and is dust made from the fossilized remains of diatoms, a type of hard-shelled algae. It is the filter media that is used in DE filters. Many of us who have sand filters use it to help filter out the really tiny dust that the sand won't catch. And, we also suggest throwing a handful in when there is a question of whether a sand filter is working properly or not. You can buy it at a pool store and maybe at Lowe's or someplace like that.

Adding DE to a Sand Filter