Milk kefir can be wonderfully unpredictable. One day it’s thick and creamy, the next it’s thin, fizzy, or extra tangy. These changes often surprise new fermenters, but they’re usually just signs that your grains are responding to their environment. The good news is that kefir “mood swings” are normal and easy to troubleshoot once you know what to look for.

Milk kefir grains are living little dynamos — but only if you treat them right. Here’s how to keep your grains active, your ferments fizzy, and your fridge full of the good stuff.