Setting up powerheads in column tank

[Saratj1]

I am going to purchase some powerheads soon for my 47g column tank. I don't feel as though my tank has adequate flow the way it is now. I am thinking about getting 2 koralia powerheads that are around 350gph each(I think they were about $45). I currently have an odyssea 250gph.
I am wondering if this will be enough for pretty much any corals I may want, and if anyone has ideas related to placement due to the odd shape of the tank.
Also my canister filter puts out a good amount of flow itself (a Rena xp4) and the output can be setup as a powerhead or a spray bar. I have it set up as a spray bar now slightly under the water pointing at a 45 degree angle up to break up the waters surface. My thoughts on this was for better gas exchange due to my limited surface area.


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[TLTGF]

What size tank is this? You want about 30-50x your gallons for a reef tank. Example: 55 gallon tank × 30 = 1650 or × 50 = 2750 gph of flow.

 

[Saratj1]

sorry its a 47g

 

[TLTGF]

So look for anywhere between 1500 and 2300gph and you should be good for just about anything. Just remember that some corals like high flow and other corals like very low flow.

Look at sites like liveaquaria to see what the corals and fish need.