Powerhead Question

totally depends on how much more flow you need.
if your just trying to eliminate a small dead spot then a small one would work, if your trying to create a lot more flow with such as a spray bar you may need something as large as a maxijet 1200. but probably not anything larger than that.

Hydor Koralias are very nice power heads to use. You can put a directional control piece on it for focused flow or let it go with out it to get a good all around flow.

I have a koralia 1 on my 37g in conjunction with a Rena XP1 and I have no dead spots. You may need 2 2's on each end since it is a long tank or one 3-4 on one spot to get the effect you are wanting.