> the balls collect a rim of sludge more easily Not sure if that's a massive issue, that would probably seal the water off even more effectively. That makes me

> the balls collect a rim of sludge more easily Not sure if that's a massive issue, that would probably seal the water off even more effectively. That makes me think that this whole balls idea will limit gas exchange too, i.e. much reduced oxygen absorption, but I guess if they want no life in the reservoir that's not an issue. Overall though I can't help feeling like there are going to be some significant unintended consequences with this scheme.