The way I’ve been making it is:
1 tbsp kefir grains = l cup water = 1 tbsp sugar
Left to ferment in a plastic container for 48-72 hours, until it doesn’t taste sweet anymore. Then bottled and kept in the fridge.
Water = mineral/spring water. Apparently the chlorine in tap water damages the probiotics. Boling tap water removes chlorine.
Sugar = Raw/unrefined cane sugar. I’ve been using demarara and molasses.
When changing the grains, I rinse them in a plastic sieve. Apparently the metal on a sieve/spoon damages the probiotics.