I'm running a Mag9.5 on my DIY 3612 and I have a little microjet in there to help keep good current. If I try and move too much more current I run into problems with bubbles making back through the tank and my overflow makes me a little nervous. This is on a 90gal tank. I would probably recommend maybe a Mag7. If you go to ecosystems web site, I believe they list flow rates for each of the models.