I'd say go with the 4, even it has higher gph but due to the much larger output area the current aren' as rush as any traditional power head of the same size. I couldn't use AC110 in my tank but hydro 4 works prefectly
Powerheads such as a AC and a maxijet are direct current ] I>~~~~~~~~~~~~~~~~~~~
Hydors are difused current and with the make and engineering of them ] '.'.'.'.I>`.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'
With my pro example and and hard thought out diagram making it ten times easier to understand should be rather simple to see. Note how there is no flow up to the first type and whenthe flow starts it is like a line, where is the hydor generates a field of current due to it's venting and design.
:cheer: I just got the HK 4 delivered yesterday from Big Al's. The p's absolutely love the extra current in the tank. I also love the HK. It definitely has the best design of powerheads for creating water current. Also, its magnet mounting system and swivel base is superb- very flexible for locating anywhere in the tank. I have used several other brands of powerheads over the years but HK has them all beat!