we have the HOT Magnum 250 which is for 30 gal
and the other is the Magnum 350 Delux, for 55 gal... something like that.
as far as they go, we have had NO problems with it, EVER. we've had the HOT 250 for a good 3 or so years now, and the 350 is on order, so we will let y'all know how it is when it gets here!!
this is the only site where i found gallon ratings, everything else had exactly what marineland.com had about the gph. hope this helps!!
http://www.aquariumguys.com/magnum.html