Many people have reports of mold and many report that it has little to no effect on your scorpion. My emperor tank has a slight amount of mold on them as well as some starting to grow. My scorpion is as normal as he always is. If you wish to prevent it, just make it so there is more air flow. Typically low air flow and lots of moisture is the cause. If you just make it so more air can travel threw the tank, it should get rid of it.