Filamentous Algae (Spirogyra)

This aquarium green algae is similar to Cladophora algae, it has strong threads, grows in a clump, BUT it doesn't have branches. Spirogyra likes aquarium plants as an anchoring media and grows very fast to cover it up.

Photos by Dusko Bojic.

Just like aquarium plants, this aquarium algae needs nutrients, enough CO2 and strong light to thrive - therefore it competes with aquarium plants for those. Luckily, it's harmless and you can easily remove them by hand.

To keep down this aquarium algae, you should do regular water change (every 2 - 3 weeks) to reduce excess nutrients, clean the filter media every week, perform good circulation, not overfeed your fishes and reduce over lighting (time / intensity). You can also put some algae eater shrimp to eat newly young algae, they won't eat the old ones.