Freshwater - Algae

Once you've establish your tank, survived the ammonia spikes and learned to feed the fish the right amount, things seem to be going perfectly.  The algae then comes to remind you that a perfectly balanced tank is an objective that you never quite reach.  Algae develops on any surface in the tank.  It is promoted by sunlight and high temperatures, which is why a dark location for the tank is preferred.  Once the algae starts, there are several ways to combat it:

• Reduce the amount of light in the tank.  Use the overhead lighting only when viewing and leave it off when you are away.

• Ensure adequate oxygenation of the tank. Consider carbon filters.

• Do regular water changes every couple of weeks, with more frequent changes when your fish populations are higher.

• Vacuum the bottom of the tank every couple of weeks and refill the tank with unchlorinated water.

• Try an Otto.  These small catfish like to eat algae all their lives and are great community fish.

• Try a Chinese Algae Eater or a Flying Fox

• Try a Pleco if your tank is large.  Unfortunately plecos grow quite large and like algae less as they grow older.  It's a common mistake to get one of these to remove algae, only to find the algae problem continues and a space problem is added.

• Try a snail.  For many aquarists, this solution is worse than algae.  Snails multiply rapidly and are hard to get rid of.

Types of Algae:

• Diatoms (Bacillariophyta) – floating brown algae that is among the first algae to appear in a tank.  These develop silica shells and are abundant in plankton. Ensure proper filtration, as they live on organic wastes.  Attempt to reduce silicates and increase marine organisms that will eat them.

• Brown Algae (Phaeophyta) – among the first algae to appear, as a matted covering over the substrate. Caused by high nitrates and silicates. Remove any sand not obtained from the ocean. Use reverse osmosis water to ensure further silicates are not introduced.

• Green Algae (Chlorophyta) – one of the most common forms of algae in fresh and saltwater.  Develops from chorophyll and nitrates.  Reduce lighting and nitrate levels.

• Hair Algae (Spirogyra and Bryopsis) – These are specialized forms of Green Algae (Chlorophyta) with light green strands that grow rapidly and attach to any surface. They thrive in the presence of nitrates, so take steps to reduce levels.

• Blue-Green Algae (Cyanobacteria) – starts in one location and spreads steadily. Caused by high nitrates, high lighting levels and organic material in the water.  For a cure, see the article below by one of our forum members.

• Brown Slime Algae (Dinophyta) – This algae can propel itself through the water and then accumulate on surfaces. This algae is beneficial for corals, clams, anemones and sponges. It can be controlled by reducing nitrates and increasing corals and invertebrates.

• Red Algae (Rhodophyta) – The is coralline algae. It is beneficial in a reef tank and thrives when Kalkwasser is used. Coralline algae helps reduce other less desirable forms of algae.

• Green Water - Free floating single celled green algae that thrive under high lighting and nitrates. Reduce nitrate levels and lighting. Increase oxygen levels. Don’t bother with water changes, as these can actual enhance algal blooms.

For pictures of the various forms of algae, visit the Smithonian Institution website.

Curing Blue-Green Algae

The following information is provided by "Littlehippygirl" from our forum:

My blue-green algae was first caused by a lot of organic debris from rotting driftwood, but even after I got rid of the wood and upped water changes, it would not go away. Not even with a 100% water change. I did a lot of research, and there was a lot of information out there and methods. I chose the non-chemical method- black out. Its been a little over 2 months and I'm still algae free and my tank is beautiful again.

Mechanically remove as much of the algae as you can and do a large water change. Cover your aquarium with a black trash bag or thick towels and turn off all lights in the aquarium. Make sure NO light can penetrate into the aquarium, and do not peek or feed the fish. Leave the aquarium alone in the dark for 4 days. Your plants and fish will be fine, and after the 4 days, the algae should be dead. Siphon out the dead algae and enjoy