the actual hydor koralia pump isn't really that much more, IMO... I would go for the actual power head, instead of just adding another $10 to your existing power head. I love the koralia's. I have a #3 and a #4 on my 55 gal. And I've just ordered 4x #4's for my 180 that I'm setting up. Here's the prices for them: nano: $26, #1: $29, #2: $34, #3: $38, #4: $45 (ranging from 240gph to 1200gph).