Types of Algae in Aquariums

At some point in every aquarium, there will be algae growth. It’s very common when the tank is going through its initial nitrogen cycle. It’s also very common after the tank is mature and has been going strong and steady for several months.  In general, there are 5 main different types of algae that grow aquariums.  Some of the types will have different strands within them, but ultimately these are the five types.

Green Water

Green water is characterized by, well, green water.  It’s the result of a single celled algae that is hanging in the water.  It is typically is the result of too much light.  It can also be the result of a high concentration of phosphates within the aquarium. High phosphates can be a result of your local water source having high levels or can come from the decay of food, fish waste, or dead plants.

Green algae is best treated by removing all light from the aquarium.  Turn the lights off for several days, keep it out of direct sunlight, and put a blanket or towel over the aquarium.  This will eliminate the source of energy that algae needs to survive and reproduce.  After several days, the algae should have died and should have been removed from your water by the mechanical filter.

Green Algae

Micropix [CC BY-SA 3.0]
Micropix [CC BY-SA 3.0]
Green algae is the generic term used to describe a very wide variety of algae growth that are all greenish in color.  They vary in the green spectrum from light to dark green.  Green algae grows on the surface of the aquarium glass or on plants or decoration.

Green algae is very common and in small amounts is not dangerous to your fish.  It can however be a bit ugly to look at.  As long as you stay up to date on your aquarium maintenance, green algae typically will not typically overtake your tank.

Green algae can be treated by turning all lights off for several days.  Like treating green water, the tank should be blacked out by putting towels or blanket over the tank.  Using an algae scraper, remove as much of the growth from the surface of the aquarium glass. Green algae is a favorite food of many algae eaters.

Brown Algae

Brown algae is very common in a new tank that is just beginning the nitrogen cycle.  The conditions created by reproducing beneficial bacteria create conditions that are optimal for brown algae growth. Brown algae thrive in conditions with low oxygen levels and an abundance of silicates.

Brown algae often will go away on its own as the fish tank becomes established with its full stock of fish and the nitrogen cycle is established.  Its also beneficial to wipe down any surfaces in which brown bacteria is observed.  This will help to reduce the population which can reproduce.

Blue/Green Algae

Blue green algae is another type of algae that is commonly found in aquariums.  While not technically an algae (it’s actually a cyanobacteria), it is considered an algae as it looks like algae and is treated using the same methods as other algae.  Blue green algae is an important piece of the nitrogen cycle.  some will attach itself to the aquarium walls and to substrate and decorations.

Blue green algae is most often caused by elevated levels of nitrates and phosphates.  Considering the cause, it is easily preventable by practicing proper aquarium maintenance including proper water changes and cleaning your tank.

Once this algae growth has started, it is difficult to get rid of.  Regular water changes will help to reduce the levels of nitrates and phosphates.  Also, treating your tank with erythromycin should help to reduce blue green algae.

Brush/Beard/Red Algae

Red algae is most common in saltwater aquariums.  It is extremely aggressive and can overtake a tank within days.  Red algae is another type of algae that isn’t actually an algae.  It is a bacteria.  Like blue green algae, it’s optimal conditions include elevated levels of nitrates and phosphates.

This algae is more easily prevented with regular water changes and routine maintenance rather than treating it after is has established itself.

If red algae has taken hold of your tank, do a large water change and turn the lights out for several days.  All light should be prevented from getting into your tank so use blankets as necessary to prevent any outside light from reaching the tank.