Musgo verde answer

You can add something like sand to help prevent this green moss or wood chips will help the growth of microhizal fungi with is beneficial to the plants root system, also helps retain water with this method saving you money/ earth.

Green moss like that is bad and is a sign of an over wet or constantly wet substrate. Wait until the top 2cm are dry before watering again and the moss will die soon enough. Follow a routine of deep watering until water comes out the bottom of the pot then waiting a few days until the top 2cm of the substrate is dry again before deep watering again. This is the correct method for growing cannabis.

Ummmm well what you have going on here is algae build up on the surface. This is caused by over watering or keeping the substrate too wet for too long. The best thing to do is get a fork or a small rake or anything that can break up the top layer and cultivate the soil. Let the substrate dry out a bit before giving more water to your plant. I don’t see algae as a benefit or a problem. It just is there and says the soil is watered too much. Anyway good luck friend 🤙