There’s a couple! The first was how differently our substrate interacts with water than expected and how it distributes water than traditional substrate, combined with the water cycle within the units. We’re still feeling it out the specific watering regimen required for our mix.

Something else extremely unexpected that happened was that we had a random weed pop up at the very end of a grow cycle! Current theory is that it came from one of our seed packets, as our substrate ingredients are inert until mixed together. It hasn’t happened before or since. I still have samples of that weed stored.

Not an issue, but I was surprised by the water cycle we have going! I knew it would happen, but for some reason the first time it happened, I called one of my friends and gushed about how I couldn't believe that a water cycle was formed.