How To Deal With Aquarium Algae

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aquarium algae

What are Algae?

In general algae can be referred to as plant-like organisms that are usually photosynthetic and aquatic, but do not have true roots, stems, leaves, vascular tissue and have simple reproductive structures.

Having aquarium algae is, unfortunately, just a fact of life. Aquariums do need some algae, but too much and it can be a potential hazard to fish and other plant life. As with many areas of life, finding the balance that works for your particular aquarium is the key to success.

How and Why Does Aquarium Algae Grow?

Algae are plant-like organisms and just like any other plant, it requires three things to survive: water, sunlight and nutrients. Algae can be referred to as the ‘weed’ of the aquarium, but is a weed just a plant in the wrong place?

One of the first signs that your aquarium is developing an algae problem is the presence of particles that are greenish or yellow-brown in color. Aquarium algae can also take the form of white or gray filamentous masses that are composed of bacteria and fungi. Your aquarium may be visited by more than one type of algae at a time, don’t be surprised to see a mix.

green aquarium algae

Is Aquarium Algae Always Bad?

No, not at all. A modest presence of aquarium algae can be considered a sign of equilibrium in your tank. When algae start to take over your aquarium it is because of an imbalance. It could be said that algae performs quite a service for you. It gives an early biological warning that something needs to be done in your aquarium to sustain plant and fish life.

The presence of aquarium algae may also have some quite considerable advantages. The algae’s photosynthesis involves the consumption of nitrogenous substances, particularly nitrates, and sometimes ammonia. While this all sounds great, the downside of their efficiency, and why they can so easily take over an aquarium is that the removal of these elements from your aquarium is also the normal role of plants in freshwater setups. The presence of algae can complement the plants’ role, or take the elements away from the plants; killing or greatly harming the aquarium plants in the process.

In freshwater planted aquariums, some fish even eat algae. Fish such as the Poeciliids and the species known as “suckers” or “washers” (Gyrinocheilus, Ancistrus, Hypostomus, Otocinclus, Epalzeorhynchus) are particularly keen on aquarium algae as a food. The other great thing about algae when it comes to introducing livestock to your aquarium is that it can help fish to acclimatize themselves to the newly-created environment of your planted aquarium.

otocinclus aquarium algae eater

Otocinclus vitattus – A great algae eater

The Most Common Aquarium Algae Types

Brown Aquarium Algae

Also goes by the names gravel or silica algae. It is widespread in new aquarium setups and coats the tank in layers. Wiping easily cleans off these layers. Brown aquarium algae are generally considered to be mostly harmless. As the aquarium matures, the brown algae will usually disappear.

brown aquarium algae

Brown Aquarium Algae

Blue-Green Aquarium Algae

Is often referred to as slime or smear algae, but is not actually an algae at all; it is a cyanobacteria. It spreads extremely quickly and can cause damage beyond repair. Excesses of nitrates and phosphates in the aquarium cause it, and you will probably need to use special water treatments to remove the nutrients, which in turn, will remove this aquarium algae.

blue green aquarium algae

Blue-Green Aquarium Algae

Red or Black-Beard Aquarium Algae (BBA)

Generally requiring a weak bleach solution (!) to kill it, this is one of the more difficult aquarium algae to remove. It is usually first noticed on plants but it can extend on hardscape materials like rocks and wood.

black beard aquarium algae

Black-Beard Aquarium Algae

Green Aquarium Algae

As far as aquarium algae go, this one is a perfectly normal and healthy algae that will be beneficial for your aquarium as long as it is not allowed to overgrow. It is also known as hair, thread or spot algae.

green hair aquarium algae

Green-Hair Aquarium Algae

Green-Water Aquarium Algae

This is commonly referred to as algae bloom as that is exactly what it looks like. This aggravating aquarium algae is a microscopic algae that is suspended in the aquarium water. It cannot be wiped or scraped off and water changes are generally not effective either. To overcome green water aquarium algae, you will need to use a diatomic filter or completely block all light from your aquarium for several days. If you take the light block route, please consider the fish and other plant life in your aquarium.

green water aquarium algae

Green-Water Aquarium Algae

Top Tips for Avoiding Aquarium Algae Overgrowth

Reduce Lighting

Placing your aquarium in a position where it will be in direct sunlight, even for part of the day will promote aquarium algae growth. Artificial light needs to be monitored to ensure that it is only as strong as is necessary and not on for any longer than eight hours a day. Consider using a timer on the plug socket to make sure you are keeping lighting levels perfect.

Reduce Feed

It is very easy to overfeed your fish and this increases water phosphate levels. Ensure you are removing any uneaten food from the aquarium after five minutes. If you are removing food after every feed, you are overfeeding.

Increase Water Changes

If there is one thing that is important to do properly, it is regular water changes. The recommended amount to change is 25 to 50% of the aquarium water weekly. This will make sure that nutrient levels in the water are kept to a minimum.

Increase Water Testing

It is really important that you understand the water that you are putting into your planted aquarium. Test the water at the source for phosphates and nitrates, and then respond accordingly.

Increase Overall Aquarium Cleaning

The minute you see aquarium algae (or even a potential algae site!) get cleaning started. Any movable items within the aquarium, remove them and scrub them hard. Glass can be scraped and gravel can be vacuumed.

Increase Numbers of Algae Eating Fish

The fun way to keep your aquarium algae under control! There are several types of fish that will help you by eating and grinding some of the algae in the tank. Plecostomus, Otocinclus and the Siamese Flying Fox are great examples.

siamese algae eater

Siamese Algae Eater (SAE) – Crossocheilus siamensis

How to Make Sure Your Newly Planted Aquarium Stays Algae-free

In a planted aquarium, it is not solely the health of the fish that you will need to plan for. Live plants require just as much, if not more, attention to keep them looking at their best; making your aquascape shine in all of its glory. While plants do process phosphates, nitrates, and ammonia as well as keeping the aquarium water quality up, algae eruptions are still possible. It is well worth remembering that algae are a plant. When you make changes to, or set up your tank for plants, you are providing just what algae need to prosper too.

Balance in your planted aquarium will encourage your desired plants to flourish; they are much more effective at taking in the nutrients in the water than algae is. Aquarium algae are well-known nutrient scavengers. They are simpler life forms than plants and are quite capable of taking advantage of unbalanced ecosystems. Your problems with algae will arise when light, CO2, and nutrients are not balanced correctly for your planted aquarium.

If you prefer to look to plants rather fish for keeping your algae issues at bay, then choose fast growing stem plants. These types of plants are well known for their ability to take in the excess nutrients in the water at a higher speed.  So, in this way, you don’t need to reduce the nutrients dosing in order to get rid of the excess aquarium algae.


Aquarium plants are also very well adapted to show that they are not in ideal conditions. Yellow leaves and pinholes in their leaves are their warning signs that their living conditions are not quite right. You really must react when you see even the first signs of the plants struggling to survive and photosynthesize. Test the aquarium water and add nutrients, where indicated, immediately. A balanced aquarium ecosystem is the result of strong-growing and contented plants.

In conclusion

As with many things in life, if it were simple then everyone would be doing it! Aquascaping takes research, time, and effort to produce amazing aquascapes. When issues such as aquarium algae arise, concentrate on working out exactly what the problem is and then work to fix it. Unfortunately, not all problems can be fixed; this is what keeps us on our toes!

aquascaing algae-free aquarium

An Algae-free Aquascape in the ADA Showroom.

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