I dont want to make a long post atm, i only have a few minutes inbetween hockey periods I just had a lightbulb go on in my brain. much like bucketed DWC systems that use airstones in each bucket, i was going to do the same with CO2 tubes. If i take a CO2 tank with an electric timered solenoid and connect that to say an 8 way splitter i could run 8 lines, one to each plant, in each of the lines what id do is wrap it losely around the stalk of the plant, all the way up and perforate the tube all the way up to the end with a little blocker on the end to give back pressure. With this system i would think you could effectively run CO2 at LESS overall PPM because it would be concentrated at all times on the plants, and you probably wouldnt even need to turn off ventilation because of the concentration. Is this a bad idea? an old idea? or an OMG WHY HAVNT WE DONE THIS YET idea?