The system will require filtration, circulating water, and other systems. Algae will thrive to the point where it clogs everything up, or the wrong type starts to grow. It just sounds like more trouble than it's worth, especially when you could add more oxygen to the air by simply going home and planting a tree.

My pond is full of that stringy algae crap, and I don't want to put anything in that will kill it because that stuff usually kills off all the little snails and other critters that I like in ponds. So, I peel it out by hand, which is the only solution I have until someone invents the Dwarf Manatee.