Diatom Filter

[returnofsid]

I'm unfamiliar with Diatom Filters but have been trying to read up on them a lil'. I understand that the primary use is to "polish" the water by filtering out particles down to a very small size. I also understand that they aren't used full time but rather once in awhile. With a few freshwater and saltwater tanks, can they be used on a portable basis, moved from one tank to the next, hung on the front of the tank, and ran for awhile to filter each one? I've read horror stories about them releasing DE into the aquarium if you're not careful. Are they complicated to use? Are they a bad idea to use because they filter out "good stuff" as well as bad? I've also read that they're effective at reducing parasites, is this correct? What features would I look for if in the market for one? Is there any problems I need to be aware of if purchasing a used one?
Any one out there that's familiar with using Diatom Filters? Any help or suggestions would be appreciated!!

 

[Curtswearing]

Boomer uses a diatom filter I believe.

I on the other hand would once per week put on Model FB1. It is a felt bag that filters all the way down to one micron. They are washable/reusable and only cost $6. The only thing you can do wrong with them is to leave it in for too many hours and have it overflow into your sump. They are especially great after you turkey baste your rock.

http://www.aquaticeco.com/index.cfm/fuseaction/product.detail/iid/4409/cid/