I'm still experimenting with mason jar whey infused kimchi. I had read that some people prefer to taste of kimchi that off gassed the CO2. I'm not sure which way I prefer it so I made a 4 quart batch leaving the top 1/4 of each jar empty. Two jars received airlocks and two are closed with standard mason jar lids. Next week I should have a favorite to share with you. Bubbles or no bubbles, that is the question.