I have been lead to believe that CO2 injection is a must, but I originally started thinking about propogation and assumed a steady flow of air would supply this. Anyway, the propogation unit I intend buying has a small sump with a pump and sprinkler system that sprays the roots, and keeps the humidity in the unit up. Will injecting the CO2 in to the water, and allowing it to be dispersed via the spray bar be a good idea? Lighting will be via 11W Arc Pods, of which I have three. I`m not sure how many I will need. The problem will be how to mount them. Space is at a premium, so I may have to go down the DIY CO2 route until I move house. So, the big questions are: Do I keep the water dosed to EI levels? Are there any other nutrients I need? Dave.