You’ve been slimmed?

Causes:

1. Silicates, Phosphates and Nitrates are all possible causes of the dreaded red slime
2. Old bulbs or bulbs in the red and yellow end of the light spectrum can also cause
3. Low flow contributes to red slime

If your aquarium is under attack from a case of Cyanobacteria aka Red Slime here are some steps you can take to fight back:

1. Increase water flow in the affected area
2. 10%-15% Weekly water changes, make sure that the water being used for the water changes is free of Silicates, Nitrates and Phosphates, use a quality test kit
3. Decrease the photo period, also a 2-3 days lights out helps a lot, and possibly changing your bulbs, depends on spectrum and on bulb life