George, I actually did look into that around a year ago. I called Nennich on the phone, and I felt pressured by him, like he was really trying to pressure me to buy. I was totally turned off to this product and decided just to stick with air stones.
I don't remember all the details, but it didn't end up impressing me as something that would be worth the expense (incl. replacements) or make a significant difference for my plants (just for pocketbook). I would have had to run it every other hour or some such thing. It sure wasn't going to fill the water with oxygen for hours and hours.