Hey DGC! I run 2 tents, veg and flower, but only run a co2 setup in flower room. At one point I tried out the TNB Naturals co2 canisters but found them too pricey for the 1-2 weeks they last. I have been running the same TNB naturals canister for the last year for c02 by refilling it once a week with table sugar, a couple tablespoons of honey (optional), and some cheap standard bread yeast from the grocery store. I use about a teaspoon of the yeast. Add about a liter of warm water to the sugar and yeast and shake daily. This will last 1-2 weeks pumping out co2 and is much cheaper than buying the bottles ever time.