Frequent Fertigation Algae/Mold

It looks like trichoderma, a beneficial fungus. Same vases I have get like that after a while, but it doesn't seem to harm plants.

does look like algae "The buildup of algae or moss on the outside usually means either you’ve been overwatering or the soil inside has become so compacted that there is little air circulation, but, in either case, that means the pots are no longer “breathing” as they should." not much you can do while the plant are growing. "Here’s how to clean a fiber pot, step by step. Dump out the soil and let the pot dry. Gently brush off the exterior with a soft-bristled scrub brush to remove dirt and stains. To get out all the soil and dried roots clinging to the inside of the pot, rub the pot sides together and dump them free or clean the inside with a vacuum cleaner. To sanitize the pot and kill any microbes, you’ll need to wash it, either in the washing machine (most efficient and much less work) or by hand in a tub or bucket. Use a laundry detergent with non-chlorine bleach or a stain remover like OxiClean to get the worst stains out while essentially sterilizing the pot. The washing machine will automatically rinse the pot, but if you hand-wash, rinse thoroughly with fresh water. Allow the pot to air dry. Do not put in a dryer."