Co2 works as above , BUT on thing that must be done regulation with a controler. They are well worth the money. I use both types tanks and gas gen's , tanks in the summer and gas gen in the winter . The room is regulated to 1500 ppm with a span of 50.
You must remember that co2 gas falls like a rock and must be moved upward in the room with a temp regulated at 95.
The main reason for regulation is death, yes death 350 people die each year from co2. If your growing in a ceilar it will be come a trap and displace the o2 in the room .
Note in a house with people and pot on the same level the co2 goes up to 500 without a problem. So just using lots of air flow does the trick.
Always remember to have a intake and exust filter to prevent the mighty damn might out.
Go with 20 pound tanks its much cheaper and easer to refill the mig welding tanks (hint )
You can get 20 pound tanks with a welding regulator and solonide from welding supply.
Grow safe Be safe and be alive