When you’re growing, it’s natural to see some mold/white "fluff" on top of the fiber. This isn’t dangerous for you or the plants, it can even be a sign of good growing conditions, but it’s not that nice to look at.
1. Remove the mold carefully with a fork, your finger, or any other tool.
In most cases, this will prevent future mold growth.
2. Remove dead plant material from the fiber.
Mold thrives on dead plant material, so by removing it you can prevent mold growth.
3. To reduce new growth, you can sprinkle a layer of cinnamon on top of the fiber.
Cinnamon can prevent mold and will not harm your plants in any way.