If the water flow in you aquarium is too great, it will blow your sand in places you may not want it to go. Corals can get buried and sand-less spots may develop, exposing the aquarium’s glass bottom. If you need the flow, but don’t want your sand all over the place, tinker with the direction the powerheads and pumps are facing. The most effective way to create turbulence but keep your sand in place is to angle the pumps toward the surface slightly or point them toward the walls of your aquarium. By aiming for the walls, the flow will be deflected. You will retain the amount of flow, in terms of gph, by the flow will be much less direct.