Any recommendations for an economical choice for powerheads? I have a 92 G corner tank. I've got 2 - Hydor - Koralia (3rd generation) pumps (2450 GPH) that I'm not overly thrilled with. I just feel like it there's not enough circulation in the tank. I may "bite the bullet" and get a Vortech pump, but if not, I'm curious what others might use that's a little more economical.