When you make kefir. You end up storing it in the fridge when it is not in use. Yiu end up with some pretty potently sour milk after a week or two. When I make bread starter. I take the kefir grains. Out of the fridge. Drain off the sour milk and reset a new ferment on the counter. Taking the sour milk left over. I mix with flower. Organic, whole wheat and rye flower an organic non glutin mix, organic oat flower, and organic buckwheat flower. I mix in about equal amounts of those flowers mixed. To the sour milk. Do I cheat ? Yup. I also have lactobacillus salivarius probiotics....and bifidobacterium breve probiotics. Do I add yeast ? No. Not necessary. But. I add what is called yeast energizer rite off the hop. 😮 Which is from your local brew store. Vit B complex magnesium sulfate yeast hulls and diamonium phosphate It is used to restart a ferment that has died back. These things. And a little sugar.. lol. Yeast loves sugar. You do not need a whole lot of anything other than kefir and organic flower. I use many different flowers all at once to get the MOST varieties of natural yeasts available. I use the yeast energizer. To make them all happy and strong. I can make an viciously active ferment in hours. Lol. One needs not add more of the yeast energizer if you can keep up to the feril appetite of the starter. And at this point. Its a race to keep it happy. Lol. I have to feed it probably twice a day on average. I keep small containers will keep one in the fridge and one on the go. 😅 This culture. Is amaising and sooooo good.