Types of Salt Water Algae

Red Algae

• Red algae, also known as Rhodophyta, are usually coralline, which means the algae often forms a hard, calcium crust over whatever object it's on. These types of algae most often range in color from pink to red but can also be brown, blue or green. They require high light levels as well as high calcium concentrations to grow. Red algae grow slowly, so they usually doesn't take over the aquarium. Red algae is considered to be beneficial, in fact, as it acts as a natural part of the saltwater aquarium ecosystem.

Green Algae

• Some types of green algae, known collectively as Chlorophyta, can form films or mats in the water and may be problematic. Overall, they are considered beneficial to the saltwater aquarium, as many types of saltwater fish or invertebrates feed on green algae. Some types of green algae are even sold as aquarium additions. You can cut it back if it grows too quickly. The three types of common, beneficial green algae include Valonia, Caulerpa and Halameda. Also called bubble algae, these quickly grow into clusters of bubbles, which must be closely maintained to prevent spreading. The Caulerpa and Halameda varieties each form leaves or stalks.

Brown Algae

• Brown algae is also considered beneficial in most cases. Also known as Phaeophyta, it can range in color from yellow to brown to black. Many types of brown algae form seaweeds, which can grow quite large. This algae commonly grows in an abundance of nutrients in the aquarium. These nutrients usually come from excess waste from the aquarium inhabitants. Although it may benefit your saltwater aquarium by providing some food, brown algae can form an unsightly film over the aquarium surfaces. Green algae and other plants should eventually outcompete the brown algae. You can also wipe the green algae away from the aquarium surfaces.

Blue-Green Algae

• Blue-green algae is actually a type of bacteria called Cyanobacteria. This musty smelling bacteria grows into slimy algae, usually blue-green in color but sometimes red, purple or brown. It grows quickly in water with a high nutrient levels and low water movement. This algae is not considered beneficial, as few creatures eat it. It can also produce toxins that poison the aquarium. You'll have to remove blue-green algae with a siphon, a partial water change or a chemical additive.

Diatoms

• Diatoms are cell algae that form brown slimes or coatings in aquariums with low light levels, high nutrient levels or poor water quality. This algae also requires high levels of silicates, so to avoid outbreaks, do not use sand or salts that contain silicates. Many invertebrates eat this type of algae and can help to control its growth levels.