I'm looking for a powerhead to add some surface agitation to a large (330g) acrylic tank. I have always liked the Hydor Koralia pumps, but I don't believe any of those have strong enough magnets for this tank - the acrylic is 1" thick. I'd like the powerhead to be as small as possible, so that it doesn't stick out like crazy, and yet still give some good flow. Can anyone offer suggestions?