would this be enough flow?

[cj7eagle]

I want to use a mag 12 in a 29gal or 40gal sump (not sure yet) and have the return line split, once line going to a 3/4" sea swirl and the other going to a spray bar that would lay across the back bottom of the tank.
I'd like to use this setup in my 72 gallon bowfront, and eliminate the need for powerheads. is this possible?

 

[trigger11]

I think what you really will want to do in your situation is calculate what your turnover rate will be in the tank
Turnover rate = GPH / Tanks Size in Gallons
So, you have a Mag-12 pump which does 1200GPH
With a 72G tank.
Turnover rate = 16.6x
Suggested turnover rate for corals is between 20x and 30x turnover rate.
So I think you would need to have another power head or two as well if you are having a reef. If no reef then should be ok.