Water Current Question (too strong?)

I currently have a dual overflow 120g tank. Right now, the returns are the only currents I am using in the tank. I am looking to add a couple of powerheads also. My question is, it seems like the pressure coming back from the return into the tank is kind of strong already, and if it catches a small fish the right way it will pretty much shoot it across the tank.

Is there anything I can do about this? Will getting the two powerheads help or hurt? I thought about maybe shooting the powerheads towards the current to push it a different way?

Any suggestions would be appreciated!

 

Here is a little lite reading that should help you understand a bit more about your reefs Flow needs.
http://www.3reef.com/forums/reef-aquarium-articles-how-tos/basics-flow-78711.html

 

that helps with flow guidelines and coral placement, but im really looking to see how to change a current and see if it is too strong. Thanks though

 

If you think the flow from the return pump is too much you can always install a ball valve and dial it back some, then add a couple of power heads to get things churning.

 

What size is your sump/fuge, and the GPH on the return pump?

IIRC, 10x the sump size is what you should shoot for. You can add a ball valve to the return line to trim the pressure, then add powerheads to achieve the proper flow for the DT.

 

You posted while I was typing... lol

 

To answer your question, we want, ideally, to mimic the ocean currents. Ocean current is described, accurately, as turbulent. To achieve this we must have a fairly strong "set" current i.e. your returns from the overflows and some counter current to oppose or at least disrupt the "set" flow. This is accomplished to a greater degree by using at least 2 adequate power heads that disperse the water, as opposed to the old out dated narrow stream that power heads were famous for. The 2 power heads (Koralia or some such type) could be placed left and right back pointed toward the center of the front glass with at least one of them slightly upward to agitate the surface of the water. In your
size tank, I would suggest 2 Koralia #5s. I hope this clears things up for you.