Rusty Algae in Saltwater Fish Tanks

Algae are chlorophyll-containing groups of eukaryotic organisms that mainly live in aquatic environments. Rusty algae commonly grows in saltwater fish tanks, especially in new tanks. It isn't dangerous by itself, but can indicate there is some problem with the water. It can also give the water a dirty appearance. Rusty algae usually goes away on its own, but a concerned tank owner can remove the algae if only for aesthetic purposes.

  1. Identification

    • Rust algae, also referred to as brown, gravel or silica algae, is red or brown in color. The algae generally begins as brown patches on the grass or gravel of a saltwater fish tank. The algae quickly expands to cover most of the surface of the tank with a thin, brown coating that is easy to rub off.

    Cause

    • An accumulation of nutrients is a common cause of rusty algae. These nutrients typically come from uneaten food, fish waste and decaying plant debris. All of these problems can be traced to improper tank care. Regular cleaning of the tank, and feeding the fish the correct amount of food will give the algae less of a chance to grow.

    Lighting

    • Algae needs light to grow, and exposing the tank to extra light, or poor lighting through improper bulbs can lead to an outbreak of rusty algae. It can also benefit from sunlight. To cut down on rusty algae, don't put the tank in an area where it gets direct sunlight, and install a timed lighting system. Schedule the lights to be on during feeding times since most fish will not eat in a dark tank.

    Controlling Algae

    • Algae will grow in all fish tanks, so the tank owner can only implement methods to keep it control. Remove any dead fish immediately since the remains contribute to the accumulation of nutrients in the tank. Keep one unclean rock in the tank to providing competition for new growth. Use an external canister filter, protein skimmer and ultraviolet sterilizer to prevent and reduce algae growth.