I am just beginning my co2 experiment. 75 gal tank. 3 2 litre bottles with 1 cup sugar, 1/2 tsp yeast, 1/4 tsp baking soda, 2 tsp honey.
Here is some advice I have picked up. 1. Champagne yeast should work better over the long term, staying alive if fed, and will just require recharging every few weeks. 2. I am using honey as an experimental replacement of 2 tsp. Powdered sports drink. This is for nutrients for the yeast. Just sugar, water, baking soda, will cause the yeast to die off. It needs proteins and vitamins to thrive, so I am told.
ALso, not all yeasts are created equally. Baking yeast peaks quickly but isn't long lasting. Brewers yeast will likely take longer to get going, but if used properly, will keep alive, requiring simply more sugar water and nutrients to get going again (quickly I might add, since you aren't starting over every month).
TAke all I have said with a grain of salt, as I just redid my system today.