don't know if anyone know "monsterfishrescue.com" that guy has a 1500 gallon, use a 55 gallon sump, and he has lots under gravel pumps, basically he just links pvc pipes all over the floor of the 1500g, and use a pump so that the poo will not settle on the ground, and when he is ready for water change or "gravel/sand" cleaning, he first use a pump and spray the surface so that all the dirts rises, then he just do a 50% water change. sounds pretty easy actually, also he does weekly water change, but when is time to clean sand, he do it once 3 month.