Green stuff on top of soil ok?

these green things are perlite that, when wet, gets covered in a thin mold. it happens to me when I make clones. basically, I have to keep the humidity very high and one watering can last me up to 2 weeks. so, not disturbing anything in the soil causes this mold to form.. by the way, I use a foliar rooting agent, so spraying it often speeds up the process.. to remove it, usually, just stirring the soil is enough so the top part gets air and dries out. for the rest, be careful if you don't water the whole pot; the part that stays dry could become water-repellent, and as a result, the water will flow over it without soaking in..