6000 going in tank. Whar height?

[Portsmouth Reef]

I am getting a 600 with a multicontroller to sit inside a Tunze stream rock for my 90 gallon. I have Cyno on the right hand sand bed in my tank. I am wondering at what height to mount the stream rock, on the sand, or 3-4 2 higher on some rock. I have some live Aragonite sand to make the sand bed deeper.I dont know how high above the sand the outlet needs to be. I dont want sand dunes up one end. Any advice welcome, On the left end of the tank I have 2 Clarkiis that live in a Devils Claw. I dont want them being blasted all over the place. If i put the stream rock 42" awaay from them, will this be O.K. Having not seen one in action I am a bit concerned about the flow.

 

[rvitko]

I would place it about 6" above the sand - mainly so it doesn't suck in sand. The stream rock gives the pump a slight upward angle so it should be fine.