I help maintain a 220 gal at my church. That tank is equipped with two M1500 on a Seio controller and two M820 that run continually. I like it because the general flow pattern changes when the 1500s throttle down, since the 820s begin to push more flow.
The only problem I have is keeping the sand from blowing around.
One thing though, you will definitely have to invest in a magnet mount unless you have a European tank.