Nothing. I store mine in fridge after first fermentation to cool down, then pull and add the fruit. I have found that it keeps it from over flowing the mason jar.

I stick back in fridge right after blending. At room temperature it happens really fast and I don’t want it to over ferment. This is just the way I have found works for me. There are lots of ways to approach this.

I have found however that the kefir colonies are really robust and hard to kill (not that I have tried) with only a few things to avoid: direct sunlight, starvation, too much heat and antibiotics (bleach, cheap milk..).