No algae doesn't hurt the plants but the simply fact is it's growing on the tops of the pots meaning the top of the media is staying to wet so you can imagine what the moisture level is in the root zone
Over watered and to much light, plain and simple, there's algae growing on your perlite, Daily or multi-times feedings a day are for big plants in small pots once the roots are established in the pots.
Yes, fabric pot allow for more evaporation of the feeds before being used by the plants. That's where build-up happens, the water evaporates leaving excess nutrients to remain in the coir.