Is Brown Algae In Fish Tank Good or Bad? Here’s Why

Before going to further discussion about if brown algae in fish tank good or bad, make sure you are well known about it.

If you are not introduced to brown algae, read the first heading first. Otherwise, you can start with the second heading.

This post will lead you to understand brown algae in your fish tank good or bad As well as some additional stuff you must know.

Brown algae is a brown, slimy substance that can usually be found attached to the sides of aquariums, decorations, substrate, plants, or anything else with a hard surface.


The type of brown algae discussed here is not part of the “true” brown algae, which multicellular algae that are in the Class Phaeophyceae, nor is it “golden” algae (which is rare, to begin within aquariums). 


Technically, brown algae are a build-up of bacteria. The type of brown algae discussed here is the common “silica algae” or “diatoms,” which are actually billions of microscopic animals built up over time. 

Diatoms do not swim in the water very well but thrive when bundled together with their kind on a hard surface. 


This is why brown algae prefer to show up on decorations and tank walls in clumps that look similar to brown dust. 


Brown algae commonly occur in newly set up aquariums with bright artificial or real light. 


And diatoms also thrive when there is an excess of nutrients in the water, and overfeeding can contribute to your brown algae problem. 


The main causes of excessive brown algae growth are excess silica and nitrates in the aquarium water.


Is Brown Algae in My Tank Good?

Brown algae are not inherently harmful to any aquarium life and in fact helps to keep the aquarium water clean by creating oxygen from CO2.


brown algae in fish tank

 Aquarium plants function in the same way to keep the water quality pristine. Brown algae also make a nice snack for snails, shrimp, or fish (specifically algae eaters), 


and if you already have this type of life in your tank, consider them the clean-up crew when it comes to diatoms.


Brown algae often grow as a tank is cycling as a sign that the cycle is maturing and coming to completion. 


This is a good sign, although it can be a bit of a nuisance. Other than these few things, the benefits of brown algae are far and few between.


Is Brown Algae in my Tank Bad?

The major downfall of having brown algae accumulate in your aquarium is that it can appear unsightly. 


Brown algae can also appear fast and without warning, alarming some new aquarists. Especially those who do not like the idea of a “bacteria build-up”, which is what brown algae essentially is, 


The thought of having brown algae take over a tank can be unbearable. It is all up to personal preference on how you like your aquascape to look.


Brown algae is a real cause for concern for those who have a planted aquarium. 


While brown algae growing on aquarium plants is not harmful immediately if not taken care of the build-up of thick brown algae can block plants from photosynthesizing properly. 


If you do not want to wait for the problem to clear up on its own or fear it will take too long, 


A soft sponge can be used to remove brown algae from aquarium plants. Brown algae are generally easy to remove from any surface, as long as it is not too porous.

How to Avoid Brown Algae?

 It can seem easy to just get rid of brown algae but it tends to grow faster under certain conditions and can become a hassle to clean up after constantly. 


There are some simple things that you can add to your husbandry in order to prolong the amount of time it takes for brown algae to build up,


Such as increasing the filter’s flow, increased cleanings, decreased light, and changing out certain decorations.


• Increase Water Flow

Since brown algae rely on surfaces to cling to and build on, turning the water flow up on your filter or getting a higher-power filter will help prevent diatom build-up. 


Diatoms are not good swimmers and are discouraged from growing rapidly in a tank with high water movement. 


It is important to find a balance between keeping brown algae at a minimum and making sure your fish are okay – they should not have to fight excessively against currents in the aquarium.

• More Water and Carbon Changes

 Regularly changing the water in your aquarium and scrubbing anything that could have built-up algae can help keep your tank looking pristine for longer.


Additionally, adding more carbon and switching out the carbon more often will help prolong the amount of time it takes for brown algae to become visible to the human eye.


• No Bright Lights or Sunlight

One thing besides excess nutrients that encourages brown algae build-up is excess light or sunlight. 


Aquariums should only be under direct artificial or real light for eight to twelve hours. 


If you are developing a brown algae problem, it is best to leave the lighting at a minimum while still mimicking the natural light of the day. 


Natural sunlight will especially encourage the growth of brown algae, which is why it is not recommended that aquariums stay near windows.


• No Plastic Plants

If you use plastic decorations in your aquarium, they may be contributing to the brown algae problem you have worked so had to combat. 


Plastic items, especially those that were not made to be fish-friendly, can leach silicates or phosphates into the water, which kickstarts a diatom culture.


A good and more natural alternative to plastic plants is silk plants. Silk plants do not encourage the growth of brown algae because they do not leach anything into the water,


 And do not run the risk of harming your aquarium life because they are softer and without sharp edges. 


Silk plants are also woven together, and the tiny holes in the fabric keep diatoms from latching on.


Brown algae can become a problem under certain conditions by growing out of control, 

But it is easily preventable and fixable as long as certain husbandry changes are met.

While not especially harmful, too much of anything is cause for concern and cleaning your tank of brown algae regularly can have good health benefits for your aquarium life.



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