Clarification - the time shuts of the diffuser in the tank. You still get occasional large bubbles of CO2, but you don't get the small easily absorbed bubbles and shutting off the diffuser also slows down the reaction.
You won't stop yeast from producing. The only way that I can think of would be to use a diverter valve of some kind. When C02 is not needed the valve would divert if from the tank and expel it elsewhere. A simple on off selenoid would work also, but depending on what you generating the C02 in is going to make the difference. If it is not strong enough to contain the extra pressure that will build up, you will have one big, stinky mess to clean up. I wouldn't recomment doing that. A diverter valve would be best.