Water kefir grains can be used in a lot of ways. You don’t just have to put them in a sugar/water solution. They work with honey, I’ve used them in green juice and here’s the result of putting them with watermelon: Watermelon kefir. . I’ve transferred it to a swing top with some sliced pear (added so its sugar can be further fermented and the drink will become fizzy) for a second ferment. . Feels a bit like pink champagne. Tastes complex – fresh from the watermelon, tart from my likeness for sour ferments (I leave them a long time) and sweet from the pear. . You do not need a juicer for this. I blended the watermelon flesh and then drained it through a sieve. . Cheers!