I know, I know...there are a ton of threads already out there on dry ice and how to use it, but after searching for over and hour I haven't found the answer to my question. I am using dry ice for a newer play version of "Les Miserable". My dad and I built our own fogger, consisting of a 31 gallon Rubbermaid container, a 4 inch duct fan which we grounded and wired to a on and off switch, and a dryer hose to carry the fog from the wing. We plan on building one more and placing one on each side of the stage. After playing around, I have figured out the more water you have, the better the fog, but what I haven't figured out is "How much do I need?". The beginning of our show starts with the scrim down and a timeline being projected on it, building up to the French revolution. We are wanting to dry ice our stage enough that we can raise the scrim, some will roll out and stand on the stage for about one minute. Our stage area we are wanting covered for this is 22'X40'. How much dry ice do I need for each one of these foggers for this effect? Also, we are wanting to use a small amount of dry ice for a graveyard scene and also a river scene. The dry ice is not suppose to be the river, but instead just an added effect and something for the lighting designer to play off of. How much would we need? Thanks!