Hi, I've been looking around for a while and it seems like the serious growers or ones with a sealed grow especially all use co2. Most of them also have nice large tanks and regulation systems. I don't have nearly the money for that, I just got a deal on two high bay 400W lights and that nearly broke me. So my question is, besides leaving open soda bottles around in the grow room is there another way to get a lot of co2 in there for em? cheaply? I've heard of spraying them with seltzer water but how well does this work? I'm willing to try anything short of sitting in the room with them until I breathe up all of the oxygen haha. Thanks in advance for your help.