Suppose you have a steady supply of dry ice arriving with orders at your place of work. Would it be possible/safe to make a storage tank for a little dry ice that, after sublimation, could then be infused into the aquarium at a constant level? If a cup of sugar powers the yeast DIY system, I'm sure a cup of dry ice will provide 10x more CO2. I just can't think of a way to do it that doesn't involve me wearing a flack jacket and a helmet every time I feed the fish
Any ideas for the technically challenged?