DE filters have diatamaceous earth in them as the filter media which is a very fine powder. Sand filters obviously use sand as their filter media. DE filters filter out smaller particles but are higher maintenance. I do not know how often DE filters need to be backwashed as I do not have one. Sand filters are the easiest to maintain and in my opinion, filter just fine. All of the moderators on the forum have sand filters however many of our other contributing members have DE or cartridge filters and like them a lot, too.

In a sand filter, you should only backwash whenever your filter pressure rises by 8-10psi over clean filter pressure. It is not necessary to routinely backwash once per week. You don't have to add sand often but every few years you may need to top it off. One misconception is that sand needs to be replaced and this is not true. It seldom needs to be done. I am on the 12th season with my same sand.