can you give me a general idea on how much baking yeast to use per volume of water for a grow room (closet 2' x 2' 6' high) for co2 enrichment. How often should I add new baking yeast? I've got a 20 oz. co2 tank for my paintball gun. Would it be a better idea to find a valve that would fit this, and barely open the valve to release co2?