Aquarium algae growth usually points to a problem with water quality. In this article, you'll learn the various types of aquarium algae and what you can do about algae in your aquarium.
It's not uncommon for novice aquarium hobbyists to turn on the lights in their new aquarium to discover that aquarium algae has turned the water in their tank green. Green water is often a result of excess algae growth and it is commonly a sign that the tank has not been cycled properly. This is just one type of aquarium algae, however, and algae growth is not limited to new tanks. Throughout your life as an aquarium hobbyist you are likely to encounter a variety of different types of algae in your tank. Each type of algae looks slightly different and its growth may be brought about by different factors. The one thing most types of algae have in common is that their growth often points toward a problem with water quality. If your tank suffers from excess algae growth it would be wise to determine what kind of algae it is and to check your water parameters to see what caused the growth rate to increase.
Types of Aquarium Algae
Brown Algae – Brown algae, also called diatoms, tend to form in soft clumps on tank walls, substrate and aquarium décor. This type of algae grows in tanks where the nitrogen levels are low and phosphate levels are high. Brown algae also grows well in new tanks and aquariums with low lighting. Manual removal of this type of algae is easy and its growth can be controlled through the introduction of Siamese algae eaters, Otocinclus catfish or aquarium snails. Live aquarium plants can also be an effective means of controlling brown algae growth because they will compete with the algae for nutrients.
Blue/Green Algae – Technically, blue/green algae is not a type of algae at all – it is really cyanobacteria. Cyanobacteria grow and reproduce quickly and they may spread rapidly across tank walls and other aquarium surfaces in the form of slimy, blue/green sheets. These growths can be removed easily by hand but if the original problem is not remedied, the rapid growth of cyanobacteria may eventually kill plants and fish.
Green Algae – This type of aquarium algae is most commonly seen in new tanks that are experiencing an algae bloom. Green unicellular algae are able to reproduce rapidly in tanks that are exposed to too much light and in tanks that have not been cycled properly. In these cases, large quantities of green algae can actually turn the water green and it may also form a film on tank walls. Though it can be easily wiped away, green algae may also go away on its own once the water parameters in the tank have stabilized.
Green Spot Algae – Green spot algae grows most heavily in tanks that are exposed to strong light. It also grows well in tanks with low levels of CO2 and Phosphate. This type of algae presents as thin, hard growths of green algae that grow on tank walls and slow-growing plants. Because it is so hard, it is not easy to remove this type of algae from the tank manually but it can be scraped off the glass with a razor blade if necessary. Algae eating fish are rarely successful in removing growths of green spot algae.
Thread Algae – This type of algae grows in individual threads that may be up to 30cm long. Thread algae tends to grow on leaf edges, often growing together with hair algae. The presence of this type of algae often indicates an excess of iron in tank water. Thread algae can easily be removed from the tank by winding the strands around a toothbrush to separate it from the surface to which it has become attached. Siamese algae eaters are one of the only species of algae eating fish known to target this type of algae in the freshwater tank.
Hair Algae – Hair algae is often light green or gray in color and it grows most often at the base of slow-growing live plants. Though it is similar in appearance to beard algae, hair algae has a coarser texture and forms matted clumps that do not move in the water current. Hair algae grows up to 4cm and can be removed manually by twirling it around a toothbrush. Many hobbyists do not mind the growth of this type of algae in their tanks because it is a nutritious supplemental food source for omnivorous species of fish.
Brush/Red Algae – This type of algae may look different in different types of aquariums. Though it may grow in either acidic or alkaline conditions, brush algae (also called red algae) tends to collect on slow-growing plants. Growths of brush algae may be up to 3mm long and it cannot be removed easily by hand. Siamese algae eaters are known to favor this type of algae, but if you do not have one of these fish, you can simply remove and discard the affected leaves of live plants.
Tips for Controlling Algae
The simplest way to control algae growth in your freshwater tank is to keep your tank clean. By performing regular water changes your tank will not only be cleaner and healthier, but the water parameters will remain stable. Tanks with stable water chemistry are less likely to see the spikes in nitrogen or phosphate levels that often precipitate increased algae growth. It is also wise to keep your aquarium out of direct sunlight and to limit the amount of artificial light you are using in your tank. If you have a planted tank, it is recommended that you leave your lights on for only 10 to 12 hours per day – if you leave them on any longer you may struggle with excess algae in your tank.
In addition to keeping your aquarium clean and avoiding excess light, introducing an algae eater to your tank is another simple way to control aquarium algae. There are several species of algae eating fish available including Siamese algae eaters, Plecostomus, Otocinclus Catfish and Chinese algae eaters. Some species of shrimp and large snails can also serve as algae eaters in the freshwater aquarium. If you choose to introduce one of these creatures into your tank keep in mind that, while it may feed largely on aquarium algae growths, you may need to supplement its diet with algae wafers and fresh vegetables.