What's the difference between EM and Activated EM? Can I keep re-activating my Activated EM?
I wish! Sadly EM is a bit different from yogurt or sourdough making. The first activation will turn out very closely similar to the mother culture, but with subsequent activations the intricate balance of microbe species and numbers will start to shift, and the effectiveness will decrease. I only ever use fresh mother culture when activating.
EM mother culture can be used the same way as Activated EM, but for economic reasons most people buy it to make their own activation. If you're new to gardening with EM and you just want to try it out, or if you don't want to spend the time and effort of activating, then go for the already activated product.