I will be putting a powerhead in a 55gallon tank. I have heard that you only need about 10 times the gallon size of your tank, which would put me at around 600. Question: is ONE 600 gph powerhead such as a SEIO good enough, or should I go with TWO powerheads such as HAGEN 50's or MAXI-JET 1200's? Honestly, I don't think I need 4 of these things like some ppl do, so waht should I get? Thank you very much to all!