I have 20 oz paintball tanks I use on my 40 gallon breeder with the GLA atomic v2 reg. It lasts about a month. I have 3 tanks that I have filled so I have to have them refilled once every 2-3 months. If I was to start again I would go with a 5lb or 10lb co2 tank and a reg for that setup. I was tight on space at the time so paintball co2 was best for me.