Papa_Tanswered grow question 3 years ago No that’s nothing really to be worried about. You possibly keep the substrate too wet. This is just algae forming on the top because it’s too wet for too long.
The remedy for this is to just cultivate your soil. So get a fork or something of that nature and break up the top layer and it should just disappear.
Try letting your soil dry out as well before giving more water.
Cheers 🤙