Cyanobacteria

Cyanobacteria is often called slime algae, but actually it's a slime mold.

If you have cyanobacteria in your tank, it is going to look like a thin dark red slimy mold covering the rock surfaces of your tank. This indicates that your tank has a very high level of dissolved organic materials, which is a bad thing.

Typically cyanobacteria can even outcompete hair algae and indicates an even higher level of dissolved nutrients than hair algae requires. In other words, your tank is very polluted.

Now I'm not talking about small localized areas in your tank where you have a tiny bit of slime algae. Often times in your system you may have a location where there's very little current flowing and you might get a touch of slime algae there. But that's usually not a problem. That's a microenvironment that has the perfect conditions for cyanobacteria

But if slime algae is covering a large portion of your tank, then you have a tremendous amount of dissolved nutrients in your tank and you need to steps to get rid of them. Visit our section on controlling the hair algae monster for more information on this.

But you begin by siphoning off as much as the slime mold as possible, and discarding the siphon water. As you remove the slime mold, you are reducing the nutrients in your tank. You can also get some sand sifters to help move the sand around, bringing oxygen to it and helping live organisms process the detritus and other waste before the cyanobacteria does.

Slime algae --> Hair Algae

Once you start to reduce the pollution level within your tank, you will begin to start to see the slime algae go away. But oftentimes you'll see hair algae starting to grow. That's because the level of nutrients in your system won't support slime algae, but will support hair algae. So it's a normal progression as your tank goes from a high nutrient one to a low nutrient one.

But you're going in the right direction, so don't get discouraged. Keep reducing your nutrients through water changes, skimming, phosphate remover, etc., and soon not only the slime algae will be gone but also the hair algae.

Just make sure that the makeup water is high quality and not adding to the problem!