Three days into batch three (Mar 19th), my kefir was bubbling like crazy, and I could already tell the grains were still growing. What I obviously needed to learn quickly was how to only make as many batches as I could drink; which would also mean figuring out how to keep/store the grains that I didn't need to use for fermenting.
The first answer/lesson was, simply, use the fridge. The basic premise being that you still need to feed the grains, so you start a new batch (make the grains food) but put the jar in the fridge to slow the grains down. So I put my three day ferments in the fridge so they could continue to ferment more slowly. As I got close to emptying each jar of liquid over the next few days, I poured the grains into the next jar, delaying the need to start any new batches.
The second answer, equally simple, was to entertain the idea of making them available to others like Kijiji/Jody had done for me. If you live in/around Winnipeg and are looking for a happy water kefir culture, let's make a trade for a freshly made batch.