20141102 Cyanobacteria (brown slime algae) problem

One of the most commonly discussed in forums for many beginner hobbyist is the brown/red slime algae, or cyanobacteria. Although they are referred to as algae, they are not really algae. Instead they are monocellular bacteria that obtains energy by photosynthesis. They will form enormous colony thus visible to human eyes without microscope with the appearance, and behavior of algae.

cyanobacteria, brown slim algae
Cyanobacteria (Brown Slim Algae)

The photo above shows how a cyanobacteria can take over the substrate (or rock work) by covering up the surface and forms a “film”. While they are considered a nuisance, they are not your worst enemy in a reef aquaria. There are plenty ways to tackle them. But to properly fight them. We first need to know what causes them to bloom.

Even though the bacteria can obtain energy by photosynthesis, like all bacteria, they also thrive under nutrient rich condition. So the two elements we can control here are: light- photosynthesis, and dissolved nutrient- food.
Three ways to effectively reduce the colony:
1. prevention- do not overfeed your tank
2. attack- stir up the sand with sifters such as goby, cucumber, nassaurius snails, or sand sifting stars*
3. elimination- with moderation, turn lights off for a day to discourage photosynthesis.
Cyanobacteria is a natural part of the tank cycling and path to maturity. There is no need to freak out when you experience a break out. Just stay calm and tackle them!

*sand sifting stars do require a LOT of sand to forage for food in order to properly survive and thrive. Please do not add one to a tank smaller than 125G.

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