Not sure if this is personal preference or whether there actually is a right & wrong way to position a powerhead. My tank is 18" x 11" x 12", and I have only one powerhead. (I was using a Tunze 6025, but as of today it'll be a Hydor Koralia Nano 900) Anyway at the moment I have the powerhead around halfway up the tank, right up close to the live rock and slightly facing upwards as hopefully you'll see from this image.

Click to view attachment

Tonight i'll be swapping out the powerheads and might have a quick play around with live rock aswell but thought I should iron out where I should place my powerhead. I want to keep the powerhead at the same side of the tank as it currently is, but would it be better to give more distance between the powerhead and rock and also the direction as mentioned.

Any feedback would be appreciated.

I prefer to have the 'head a little further from the rock. I figure that if you put it right up against the rock, then most of the powerhead energy is deflected by the rock, whereas if you put it further away there is a better chance of the 'head creating more of a circular gyre in the tank, which keeps things moving around throughout the whole aquarium instead of one high-energy spot.

Thanks for reply, I'm glad you've confirmed that for me, I ended up putting the powerhead in opposite corner to the main rock and happy with results so far.