Let's talk about how a pre-made bioactive substrate can really up your chances of having a successful terrarium in the long-term. The health of your plants, clean-up crew, and critter all depends on the soil mix and how long it retains its nutrients. The Dude has put in the testing and research to create bioactive substrates that last 10 years with minimal maintenance. This keeps you from having to replace your soil mix because it got depleted. Why risk having to constantly replace all your soil