I don't think I've ever actually used the stuff myself, but I've had a brick sitting around for almost a year now and decided I could use it for a couple new millipede habitats. It says on the package to let it soak in 3-4 liters of water for 30 minutes and it'll be good to go. Um, no. 3 and a half hours into it, an extra liter or so of water, and some manual breaking-up of the brick, and it's still a brick. It's supposed to soak up the water and turn into a nice soil-like substrate. Has anyone had better luck with the stuff or is it always this difficult to work with? I'm sure it makes a decent substrate, but that's no good unless I can actually get it to that consistency.