I use two of the 1/2" stubbies on my 15g sps tank. They are mounted on the back and shoot to the front. I use the Y nozzles which breaks up the current some. But the main thing about seaswirls is that you can use different sized pumps as the motion is not dependent on flow. I use about 325 gph each on mine which is at least 200gph less than their max rating if I remember correctly.
