How to get rid of green spot algae (GSA)

Green spot algae (GSA) looks like tiny, hard green spots on the aquarium walls and slower growing plants that are very difficult to clean off. A lot of things can cause an outbreak, such as too much light or an imbalance of phosphate. Try using a glass-safe or acrylic-safe algae scraper (with the blade attachment) to remove the algae from aquarium walls.

Nerite snails are also a good first line of defense since they seem to like eating GSA. Just be aware that, while this species does not reproduce in freshwater aquariums, they will lay white eggs (similar to little sesame seeds) all over the aquarium, and some people don’t like the look.

For more information, read our full article on how to fight algae in your fish tank.