Powerhead placement

Should powerheads be placed on the same plain in the tank or at different levels?

 

IMO, every tank is different! Varying live rock and coral palcement and growth can alter the water flow from powerheads!
Your best bet is to create a turbulent flow while at the same time avoiding the laminar one directional movement. I like the placing of powerheads so that the water flow banks off of the glass. This helps to disburse the amount of water over a larger area as well as avoiding the strong stream usually associated with powerheads, that could injure coral by either causing the polyps to not extend fully or possibly causing tissue to separate from the corals calcium carbonate skeleton.
I do like the idea of positioning powerheads at varying levels within a tank hough!

 

I've often wondered that too! What a good answer! Thanks!