Balconies catch dust, rainwater, plant debris and sometimes detergent runoff. If water stands around or surfaces stay damp with organic matter, algae and moss start growing—usually as green, slimy patches. These look bad, but more importantly, they’re slippery.
Regular sweeping to remove leaves and soil, and nudging water towards drains so it doesn’t stagnate, keeps surfaces drier. Drier floors give algae less chance to settle and spread.
This doesn’t mean you’ll never see any growth, but you’ll avoid those dangerously slick areas where one careless step could lead to a fall.
