well if u already have sand moving around, another 1200gph sure is not going to stop that. i have a 1000gph return pump. with that and 6 MJ1200's, i'm at about a 35X turnover. when tank was new i would get sand storms alittle but as it aged, sand has settled. only now i am considering throwing in a tunze w/ another 1200-1300gph. i will probably have to hook up to controller though and slow down a bit. if i were u i wouldn't add anything until sand is settled. how old is your tank? why do u feel u need more than 40X turnover anyway? what are u keeping? if i was at 40X i wouldn't change anything, it's more than enough. IF i add the tunze i'll be at a 50X turnover. that would definately be all for me. i may not even do it since my RBTA is settled in perfect spot, and corals seem happy already. if i didn't have the RBTA, i would definately get the tunze, corals i'm sure wouldn't mind. i wish when i set up tank that i just bought 2 tunze streams instead of 6 MJ 1200's. good luck. just remeber if sand is blowing now, it's only going to blow alot more if u add another 1200gph.