Originally Posted by Searchin
Thanks everyone for your input! Some follow up questions:
If I'm understanding this correctly, the Danner mag 7 has 700GPH and I need at least 500GPH to maximize efficacy of the reef octopus 150 so that should be good right?
Also why do you recommend a return pump that hangs over the top rather than cutting a hole in the glass for the return?
Why drill an extra hole in the tank when you don't have to? Every hole you drill is a potential leak point. Plus, when the power goes out, the return line will back siphon until it sucks air. If you have it 4" below the surface, 4" of water will drain into the sump. People rely on check valves for this, but I would not trust them in a salt water application. Too many things grow in dark places in these tanks. I would keep is as close to the surface as possible.
As far as the mag7 question, you would have to consider head loss as well. How far will this be pushing water up and how many turns will the water have to make before it is expelled?