Black Beard Algae (Also known as Black Brush Algae) is a common issue for many aquarium owners. Even a small amount of this fast spreading algae will overtake anything it can get a grip on.

Causes of Black Beard Algae

Black Beard Algae often arrives into plants that came via another tank containing Black Beard Algae. The problem can quickly become an epidemic under the right conditions. Fluctuating CO2 levels, low nutrients in the water, too much light and more can all lead to a Black Beard Algae bloom.

Black Beard Algae Removal

The worst part about Black beard Algae is that it is really hard to get rid of.  Fortunately, there are a few things you can do to help kill this algae, and keep it under control.

Fixing Your Tank

The first thing you need to do is try and get your tank conditions back on track. Here’s some steps to stop your tank being quite so algae-friendly.

Stabalize your CO2

The most important thing you need to do to stop algae growth in an aquarium is stabilize the CO2.  If you’re adding CO2 in to the system, up the amount.

If you’re using yeast based CO2 injection, it’s time to switch that out to a pressurised system at least a month to counter the instability of a yeast CO2 unit.

Add the Right Plants

Consider adding Hornwort or other highly active, fast growing plants. These can compete with the algae for key nutrients, helping keep those algae levels down. (This won’t be enough by itself to kill off the algae, just help keep it in check).

Fix the Light

Cut down your lighting by a couple of hours, this shouldn’t hurt your plants, but it will definitely cut down on Algae growth.

Check Water Flow

Low water flow may leave areas of your tank lacking in carbon and nutrient levels.  These low nutrient areas stop plants from growing, leaving the field clear for algae growth. Consider your filter positioning or an aquarium circulation pump to help fix those dead spots.


Though most aquatic plants will die if left out in the open, aquarium decor, rocks, and driftwood can be set out to dry in the hot sun. Leave these out for a few hours and there’s a good chance it will kill off the algae.

This is not a permanent solution, however, since it’s most likely residing in other areas of the tank, but you should do this if you are having to chemically treat areas of the tank.

Black Beard Algae Eaters

There are not many fish that will feast on Black Beard Algae. Larger Pleco’s will sometimes chow down, but for guaranteed results, your best bet is a Siamese Algae Eater, these handy fish can get pretty large, but they are fantastic at eating Black Beard Algae and will easily keep even large black beard algae infestations under control.

The downside is that because of the size of these fish you really need a minimum of a 50 gallon tank for a full sized Siamese Algae Eater.  You may however be able to borrow one, or buy a younger fish and return it when it gets too large for store credit.

Chemical Removal

When all else fails there are ways to chemically treat your tank to help remove black brush algae. There are a few treatments available, but try and remove as much as you can by hand, before treating the tank.


Turn off tank filters, leave them off for around half an hour after treatment.

Add 1.5ml per gallon before the lights go off, you can increase this to 2.5ml per day if needed, but it may harm your shrimp and other smaller fish!

If it’s in specific areas of the tank still, add 1.5ml to a gallon of water in a container and use a baster to directly treat affected areas.

If you have scaleless fish cut the dosage in half.

Metricide 14

Add around 0.8ml per gallon to the tank/container and treat as with Excel.


H2O2 (Hydrogen Peroxide) is effective at killing off BBA, but it can also be harmful to other tank creatures.  Because of this, first try spot treating areas of the tank.

To spot treat black beard algae with H2O2 add around 3ml of 3% H2O2 per gallon of water in a container, turn off the filter and all pumps, baster the affected areas, and after around half an hour do a 50% water change .

If this doesn’t work, or the Black Beard Algae is tank wide, add around 2ml of H2O2 to the tank then do a water change, do this weekly until the algae is all gone. Keep a close eye on your fish, high levels (4% and above) can ill fish.


Bleach is a last resort, but can be used on any non-porous items in your tank. Use around 4% bleach mixed with water. Dip all on alive, non-porous items in here, and leave overnight.  Rinse these items thoroughly after the dip, soak them in water and a dechlorinater as well to make sure.