If your Kefir Grains are converting milk into kefir, doesn’t smell rotten and grow in size and number then you know that your Kefir Grains are most probably healthy. A yeasty smell, stringy appearance is a normal variation and is a result of a stressed grain usually this happens with the change of season, change of milk. They may also stop growing for short periods of time but they usually they adjust quite well and rebalance themselves without help. If they start smelling rotten or not converting milk into kefir then you may want to give them a milk wash, place them in fresh milk and put them in the fridge so that they can recover. Leave them there for 3 days up to a week and continue brewing your Milk Kefir as you usually would.