I have a power head in my 29 gallon FW tank for 2 reasons...
1) To disperse my C02 into my tank easily
2) Provide extra mechanical / biological filtration
It is in the same corner as my heater and intake for my Aqua Clear 70 and outputs at a 45 degree angle. The current level is set to medium and it does a great job of moving the water through my plants. The fish seem to have found "new" resting spots since I added it but they also seem very happy about the addition.
Just my 2 cents on the subject.
