I had my kefir in a closed mason jar in the fridge for about a week or so. WHen I opened the lid it popped from carbonation. The kefir was very bubbly and tart. I used it to make cornbread which was yummy. So why did it get fizzy? Do I need to store it in an open container in the fridge? My DS was excited to get a honey kefir drink but he didn't like the tart taste with bubbles.
If you keep your kefir tightly lidded, either in or out of the fridge, it will get fizzy. To avoid the bubbles, cover it with something that breathes, like cheesecloth. Or leave the lid on loosely (that might only work somewhat, I'm not sure.)