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How to get rid of algae in your planted aquarium?

How to get rid of algae in your planted aquarium?

Posted by Modern Aquarium on 16 May 2023

In our previous blog, we wrote extensively about what causes and how to prevent algae problems in your aquarium. We strongly recommend that you read that blog first because, as Benjamin Franklin famously once said, an ounce of prevention is better than a pound of cure. But, even if you already have an algae problem in your aquarium, do not be discouraged because many of the steps recommended in our previous blog will either slow or even resolve your algae problem in time. We will also cover many other effective ways to combat unwanted and unsightly algae already present in your aquarium in this blog.

Many types of algae may afflict home aquariums. All of us, novices and experienced aquarium hobbyists, experienced at least one type of algae at some point in one of our aquariums. As effective algae treatments may vary from one algae to another, we will cover them separately, describing those that were most effective and worked best for us.

1. Cyanobacteria

Ironically, cyanobacteria are not algae. Rather, it is a type of photosynthetic bacteria. In common parlance, it is often referred to as blue-green algae. This name aptly describes this algae’s appearance as when it grows it often creates large, slimy sheets in dark green or almost blue in color smothering everything in its path, including plants, gravel, substrate, and other aquarium decorations. Left unchecked, cyanobacteria will cover everything in its path and kill all plants. Blue-green algae is also easily recognizable because it emits a distinctive foul odor that smells musty or as if something is rotten.

Blue-green algae is believed to be caused by a combination of factors. The most important factor appears to be a build-up of excessive decomposing organic matter, such as left uneaten fish food and fish waste. Excessive light and poor water circulation are also contributing factors.

Cyanobacteria is not edible and no fish or snail will come even close to it. However, the treatment is pretty straightforward and effective. Begin with removing or vacuuming as much of the slimy film as possible. It is not firmly attached so it is fairly easy to remove large chunks of it and quickly. Next, clean your aquarium filter (especially a canister filter if you have one) and perform a large water change to remove excess nutrients from your aquarium water. Once you removed most of the algae, medicate your aquarium with erythromycin. Recall that blue-green algae are a type of bacteria and not algae at all, and we found that the most effective treatment is the application of the antibiotic Erythromycin. It is an antibiotic that stops the growth of bacteria and is generally very safe to use in home aquariums. In addition to treating various fish diseases, it effectively inhibits growth and even kills Cyanobacteria. Use Erythromycin as directed and you should see the results within days. This treatment can be repeated.

Because cyanobacteria are photosynthetic bacteria that require light to grow, you can also starve it by completely blacking out all light. If you decide to do it, cover all sides and top of your aquarium completely so that no light enters your aquarium for a period of about 3 full days. At the same time, increase water movement or surface water agitation, and do not feed your fish (they will be fine). Cyanobacteria will die off without access to light. We found this method less effective than using Erythromycin and entirely unsuitable for planted aquariums as the lack of light for an extended period will also negatively impact your aquarium plants.

After the treatment, and if you correct the root causes that allowed the cyanobacteria to grow in your tank, your aquarium should be free of it going forward.

2. Black Beard Algae

Black beard algae or black hair algae produces approximately half to one-inch long and densely packed tufts of brown or black strands of hair-like algae. It can grow on driftwood, gravel, aquarium decorations, and even on the leaves of broad-leaf plants like Swords and Anubias. Like most other algae, it grows in aquariums with excess or nutrient imbalance. It typically is not a fast grower, but once established it is one of the most difficult algae to remove. Indeed, physical removal of the algae is very difficult or nearly impossible unless you remove the affected item from the aquarium and scrub it vigorously with a heavy-duty scrubbing pad. Even then, the task is difficult and time-consuming.

If at all possible, remove the affected item or decoration from your aquarium and let it dry for a few days, killing the algae in the process. Then, scrub the rest of it and place the decoration back in your aquarium. If it grows on the leaves of your aquarium plants, trim and discard the affected leaves.

If the item or decoration cannot be removed from your aquarium a couple of other methods can be employed to destroy the black beard algae. Black hair algae can be killed by applying hydrogen peroxide on the algae. If you can temporarily drop the level of water in your tank to expose the affected areas, you can apply hydrogen peroxide with a small artist's paintbrush. If, however, this is not an option, you use a small syringe and squirt hydrogen peroxide under the water directly onto black beard algae. You may need to repeat this treatment several times. After a couple of days, black beard algae should start turning purple, then white, and then die off within one week or so.

Only one fish – Siamese Algae Eater - is known to eat black beard algae. However, if given a choice, Siamese Algae Eater will prefer flakes or pellets and other more palatable fish foods or algae. In our experience, for the fish to turn its attention to black beard algae as a food source, the Siamese Algae Eater must be quite hungry. You will encourage and coax the Siamese Algae Eater to eat black beard algae by withholding fish food for a few days and up to even a couple of weeks. You need not worry about your fish starving to death as the fish should be fine without food for a couple of weeks, and there’s usually enough leftover food in the tank anyway.

Black beard algae is probably the toughest, but not impossible, algae to get rid of. As always, maintaining a well-balanced aquarium will help prevent algae problems from occurring. Consider having live aquarium plants in your aquarium. They will absorb excess nutrients, keeping your aquarium balanced, and making it more difficult for algae to grow. They also look beautiful and are much appreciated by fish.

3. Green Dust Algae

Green Dust Algae or Green Spot Algae is commonly present and visible on aquarium glass. Appearing as small green dots, they annoyingly cover the viewing area and may be quite unsightly. But, this type of algae usually does not grow on other surfaces in the aquarium.

Green spot algae usually grows when good light and excess nutrients are present. Correcting these two triggers will effectively inhibit any future growth. And the treatment is also easy. Simply use a scrubbing pad or algae scrapers such as Mag-Float Glass Aquarium Cleaner or a razor aquarium algae scraper to remove it from the glass.

Some algae-eating fish like plecos and algae-eating snails like mystery snails will graze on it, helping you to keep your aquarium clean.

4. Brown Diatoms Algae

Brown Algae, called by some as Diatom Algae or Silica Algae is commonly found in new aquariums. However, it can also grow in established aquariums where nutrient imbalance is present, causing this algae to flourish. Brown algae looks like a thin brown film and can grow on any surface including the leaves of aquarium plants.

Fortunately, it is easy to deal with. You can simply wipe it off from any surface even with a wet paper towel. However, we found that employing an army of brown algae-eating fish or snails is most effective and, honestly, requires no effort in the long run. Algae-eating snails such as Mystery Snails and Tiger Eye Nerite Snails are particularly good at devouring brown algae. They are so effective that a group of them will have no problem keeping your aquarium clean. Similarly, Otocinclus Oto catfish, while a diminutive fish, is a voracious brown algae eater that will keep this pest off of your aquarium plants or decorations.

5. Hair Algae

Hair Algae is a generic name for a wide range of algae, including staghorn algae, green hair algae, and filamentous algae. They all are characterized by long and thin hair- or thread-like growth that can smother other aquarium plants or even get entangled in aquarium equipment like filter intakes.

The first course of action is to attempt to remove it from your aquarium, or at least as much as you can. You can use anything but we found that using aquascaping tweezers makes the task much easier. Simply grab and try to wind or entangle the thread-like strands of the algae around the tweezers and pull it out of the water. Admittedly, removing hair algae is a tedious task but the more you remove it, the more likely you are to be successful at eradicating it from your aquarium.

Afterward, clean your filter, make a large aquarium water change, and keep your aquarium in balance by doing regular aquarium maintenance. It is also important to have a proper level of lighting. Too much light will encourage algae growth and make keeping it in check exceedingly difficult. For these reasons, we recommend investing in good-quality aquarium lights with the proper light spectrum, intensity, and built-in timer.

Liquid algae killers can also be employed in conjunction with the various treatments described above. If you decide to use them, please follow the use instructions.

Most, if not all, algae problems in aquariums are caused by an imbalance of nutrients and light. Having a properly balanced aquarium will prevent most algae from becoming problematic in your aquarium and make aquarium hobby more enjoyable. Live aquarium plants, particularly fast-growing plants like Hornwort, Wisteria, and Amazon Sword, and floating plants such as red root floater and duckweed will efficiently remove excess nutrients from the water in your aquarium and help you keep it in balance. Live aquarium plants are a perfect example of combining beauty with function and should always be your first choice when furnishing your aquarium.