What causes Algae in Aquariums?

There are three things needed for algae to grow in a fish aquarium: water, light and nutrients. Since all three are also vital to the fish, you can't eliminate them, but there are steps you can take to help minimise algae growth.

Water

When algae growth appears, make an initial 20% water change for five to seven days until the water is clear again. Once the algae are gone, continue to make a 20% water change twice a week to help prevent growth from recurring.

Light

If you're using a hooded light, place the light on a timer and minimise the amount of time the light is on. If your aquarium is in a sunny spot, move it away from direct sunlight or place something over the side of the aquarium receiving the most light.

Nutrients

When fish eat, they produce waste in their water, which produces nutrients for algae. So it is important not to overfeed your fish. Also, be sure to remove any dead fish from the water immediately, since the decay is not only unhealthy for the other fish, but adds more nutrients for the algae.

Algae-eating fish

There are several fish that eat algae such as Siamese Algae Eaters and Plecostomus Catfish (Pleco) that can be helpful in managing the amount of algae in your tank. It is important to realise, however, that the Pleco can become very large and the 8cm fish you brought home for your aquarium may eventually become more than 30cm long.

Chemicals

There are several chemicals on the market that will help with the removal of algae, but it is best to keep the aquarium as natural as possible. Water changes, light control and keeping the aquarium clean are the best defence in keeping algae from returning.