Quote Originally Posted by Bleach=Chlorine?
I think we are dealing in semantics here. Unlike a sand filter where the sand = the medium a DE filter has grids which get coated with DE. It is these DE coated 'fingers' that filter, clean and polish the water. The DE is not a chemical that is going to clarify the pool... it is about as inert as you can get.
actually a 'filter medium' is the substance that does the filtering and the filter is the unit that holds the filter medium...so in a sand filter the medium is filter sand, In a DE filter the medium is DE (the grids just hold the DE in place while the filter is running), and in a cartridge filter the medium is either Reemay polyester (bet you weren't expecting that!) or (in cheap ones like the Intex doughnut's filter) paper. All these are considered mechanical filters. They physcially trap the dirt and remove it from the water column in exactly the same way. The only difference is in how small a particle they can trap and hold. Zeolite, used as a sand replacement in sand filters, is a mechanical AND chemical filter because of it's ability to bind ammonia to it in addtion to trapping particles.