I'm setting up a 70 gal tank and am thinking of running Tunze units for flow. The tank is 3'Wide x 2'Tall x 1.5'Deep. With a tank that small, what type and model # would work well. Would (2) units work, one in each back corner w/ a controller to switch amount of flow to each unit? I don't know if the smallest unit available would cause a sand storm in my tank, even w/ 1 unit. Any and all advise is appreciated as I am not very familiar w/ Tunze.