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Controlling nuisance reef aquarium algae is something that most if not all reef keepers have, at one time or another, had to deal with. A lot of time, effort, and money has been spent on ways to prevent it from taking over reef systems, and if it does become established, on eliminating it.

Essentially, they are organisms that produce their own food by a process called photosynthesis. There are many forms. These range from kelp to caulaerpa to those brown dots growing on the panels of glass in your aquarium.

Some of the more crucial factors that affect growth in your reef aquarium are light, water flow, nutrient concentrations, and competition for those nutrients.

Of all these factors, light has the greatest impact. A typical coral reef in the wild has very high light intensity. One way to kill algae, is to deprive it of light. In your reef, the quantity, spectrum, and duration of your lights all influence not only what types are present, but also, the abundance.

The level of nutrient concentrations also has a big impact on populations. Many types of hair and slime algae will start growing in response to excess nutrients, especially nitrates and phosphates.

Water flow or the lack of it will contribute to film algae growth as well. One well known way to control some of this growth is to increase the water flow throughout your tank.

The typical type you don’t want are called Micro. These range from diatoms (the brown dots on the glass), filamentous (hair) and smear or slime (actually cyano-bacteria) algae.

There is however some types that is actually beneficial to have. Macro's such as Chaeto, Caulerpas, Halimeda, and Kelps can be an attractive addition to the reef tank, and provide a valuable food source to many of your fish and invertebrates.

Chaeto, which is the best and easiest for this job, is typically grown in a part of your sump called a refugium. This section is a refuge not only for your chaeto, but also for many other animals such as pods, beneficial bristle worms, snails and a good place to put troublesome fish.

Take a look at the following links and learn about the different types of reef aquarium algae.

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Diatoms

Green Hair Algae

Cyanobacteria (Red Slime)

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