[PrairieReefer]

I use a Magnavore 6 (rated for up to 3/4 inch glass I believe), on a 75g with 1/2 inch glass (completly open top, no bracing or euro bracing, a very nice tank). I would never go back to anything else. I even use it on my tanks with 1/4 inch glass. It is a little harder to move, but nothing sticks to the glass after a pass with it.

Also, cleaning the exterior of the glass with Coralife aquarium glass cleaner and polish alows the magnet to move a lot easier. I don't know what is in that stuff but it almost seems like a teflon product or something. Makes the glass real slippery and dirt, salt and fingerprints don't stick as easily. (I am fanatical about keeping viewing surfaces spotless - this includes my glasses, windshields, and my aquarium front panes).