How to Get Rid of Cyanobacteria (Red Slime Algae) in Your Aquarium

Cyanobacteria, often called red slime algae, can spread quickly across aquarium surfaces. A steady, multi-step response works better than relying on one fix: remove what you can, reduce excess nutrients, improve circulation and filtration, and use treatments carefully when needed.

Steps to Control Cyanobacteria

1. Remove it physically. Siphon cyanobacteria from aquarium surfaces during maintenance.
2. Perform water changes. Increase water-change frequency and use RO/DI water to help reduce nutrients that support growth.
3. Check nutrient balance. The source guide recommends aiming for phosphate below 0.10 ppm and nitrate below 5 ppm. Test your water and avoid making abrupt changes.
4. Review lighting. Adjust the lighting period or intensity if appropriate for the animals in your tank.
5. Review feeding. Avoid overfeeding and remove uneaten food.
6. Improve aeration and circulation. Better water movement and oxygen exchange can support a healthier system.
7. Maintain mechanical filtration. Remove suspended debris and clean filter media as needed.
8. Support beneficial bacteria. Consider an aquarium bacteria product such as Dr. Tim's saltwater bacteria.
9. Use chemical treatments cautiously. If you use a product such as Chemiclean, follow its label directions and observe your aquarium closely.

Addressing the underlying maintenance and nutrient issues helps reduce the chance of recurring growth. Test regularly and make changes gradually to protect aquarium inhabitants.