Tim,
I would use extreme caution when dealing with these power heads. I am not one to bash vendors. But, Dobbs who posts here had a very nice tank that was thriving. He started losing things then had a major algae outbreak mean while all his numbers held true. Then finally it just crashed, losing most coral several fish and most every snail. Several folks looked at the tank including philip and nobody could pin point the issue. Thinking it had to be something in his water. Well finally Dobbs moved that power head while doing a water change over to one of his big trash cans to circulate water. He was about to reach into the water unknowingly to adjust the powerhead and right before he hit the water he noticed the hair on his arm rise, thinking that wasn't right he grabbed his meter, and he will correct me but I think he said it was dumping 14 volts into the water container. Needless to say his tank is literally dead, 90 gallons of it. I am sure there are many that are not doing this but you might want to look it up this seems to be an issue with several people. Sorry for the long post but after looking at his tank I don't want that to happen to anyone. Remember this was something that started slow and went on a long time probably just dumping a little more voltage each week.