Pretty positive it would. I have a Fluval 305 on my 40 gallon, it is suggested for 70 gallons and definitely circulates the water enough. Having one for more gallons than the tank, is the way to go in my opinion because once it's stalked and fully loaded it ends up equaling out, so I'd imagine the only question would be what your stocking was, but I can't imagine that you'd be so overstocked that you could make that 210 gal, turn into an equivalent of 400 gal. :]