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How To Get Rid Of Brown Algae | Prevention & Removal Guides

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Brownish color, ugly looking micronism, with roots like that of plants. Welcome the new intruder of your fish tank called brown algae. They are also referred to as Diatoms and they can be extremely difficult to get rid of in the fish tank. Although they are among the most dreaded creatures of the fish owners, however, they serve as a good source for the fish if they are not too much.

For one, removing them manually can be tedious as they cling tightly to their host in the tank. Also, they are generally bad- looking and can pose serious health problems to both your fish or plants especially if there are plenty of them spreading over everything in the aquarium. How to get rid of brown algae? This is most likely the question bothering your mind right now and this is what lead leads you to this article. However, you need not panic. With the right care and maintenance, you can get rid of these terrible creatures. Read on for the full scoop!


What is Brown Algae anyway

Brown algae come in olive green or brown depending on the dominance of the pigment in their body. They vary in size and this ranges from a small seaweed to a large complex size. They are commonly found in new tanks or aquariums. To know if your tank is having brown algae, gently rub your finger on the glass, if you notice any soft slimy thing, say hello to your new friends. Frankly, they have always been in the water, they just need the right environment to grow. Moreover, these creatures cannot swim, they only cling tightly to the aquarium glass, decorations, plants or any stable surface in the aquarium.

Most people confuse brown algae and diatoms due to the fact that they can both thrive under sunlight and they can be a pain in the neck when it comes to eradicating. However, diatoms consume silicates to grow while algae do not. Also, another problem fish owners encounter with diatoms it that no matter the number of times the light is off, diatoms will still survive in the diatom aquarium. Moreover, when you think you have succeeded in eradicating some amount of nitrates in the water this stubborn creature will still live on silicates.

Causes of brown algae

Brown algae in fish tank, How? Well, there are various factors contributing to the development of this annoying thing in your fish tank. Understanding the causes will help you to take necessary steps in combating the problem.

High Level Of Silicates:

Excess silicates in the water is a bonus for the diatoms. They will consume the silicates and just die but the thing is this might take months.

  • Using tap water that is high in silicates acid is one way to increase the number of silicates in the water.

  • Introducing of sand-like play sand or pool sand to the substrate will increase the silicate in the fish tank.

  • Using salt mix will spike up the silicates in the water. Read the label and ensure the salt mix does not contain silica before using them.

High Level Of Nitrates In The Water: 

Nitrates are part of the nitrogen cycle and nitrates build-up occur when you fail to constantly change the water in the fish tank. Not only does high nitrates charge up brown algae, but it is also harmful to your pets as it weakens the immune system. Other things that can increase the level of nitrate include

  • Overpopulated habitat.

  • Decayed material and food, fish poop are also sources of nitrates.

  • Plant fertilizers consist of high concentrations of nitrogen. Be careful when you are introducing them into the fish tank.

Inadequate Exposure Of Diatom Aquarium To Light:

Inadequate exposure of your fish tank to the lighting can cause an algae bloom. Unlike the green algae, brown algae thrive in dim light. A light timer will be of great help to ensure that your fish are getting enough light.

High level of phosphate:

All living creatures depend on phosphate for survival and there is no way you will want to get rid of them if you want a successful fish breeding. 

Pro Tip

The bad news is a high level of phosphate can lead to the bloom of algae and diatoms in the fish tank

This happens as a result of the presence of uneaten food, dead plants, dead fish and fish feces. Ensure your tap water is tested to know the amount of phosphate present in it.

How to get rid of brown algae( Diatoms)

The application of these methods or steps is a good solution and will answer your question on how to get rid of brown algae.
  1. physical removal

    Although this can be time-consuming, it is an effective way of removing brown algae. You will have to roll up your sleeves and get down to the business of removing this stubborn thing from your fish friends home. You can use your hand or scrubbing pad to wipe off any brown algae on the glass.

  2. Change the water in the tank

    A constant water change will help to reduce the number of nitrates and phosphate that can help in the growth of algae. About 20 percent of water can be removed and replaced with clean tested water. Use reverse osmosis or deionized water to replace the water in the tank. These techniques ensure there you are not adding to the supplements that are favorable for the growth of algae.

  3. using vacuum

    Vacuuming of the gravel is also a good way of removing brown algae that are on the gravel. You can use a siphon to vacuum the gravel or any other aquarium decor present in the tank. However, light vacuuming is recommended if you don't want to kill the bacteria that might be beneficial for the fish.

  4. get brown algae eaters or critters

    If you don't mind having an extra pet in your fish tank, you might as well get new companions for your fish. Catfish, snails, Siamese algae eater, Otocinclus and lot more are brown algae eaters that will find algae a good meal. They are quite effective as they will consume algae that are burrowed in rocks, ornaments, sands and even glass. However, you cannot always rely on these animals in getting rid of the algae. Are they compatible with my fish? Will the habitat be crowded if I get them? Will they find these fish friends or food? These are the questions you can ask yourself before introducing critters into your aquarium.

  5. avoid contributing to silicates

  6. Each time you are adding the salt mix to your aquarium, ensure they are silicate free as you don’t want to contribute to the growth of the brown algae in your fish tank. Moreover, adding live sand or live rock is like laying a welcoming rug for an algae bloom.

    One effective way to reduce silicon and phosphate is to use phosphate adsorption resin in the filter to ensure a silicate free water in the aquarium.

  7. lightning

  8. Supplying appropriate lighting for your pet is one thing you can do to eliminate brown algae. Eight hours’ exposure to lighting per day is okay, however, if you don't have any other live plant in the fish tank, you can reduce it to six hours.

    One good way to balance the lightning is to fix an ultraviolet sterilizer that will act as normal sunlight. They have no side effects on the fish but will rather kill any bacteria or brown algae that might be present in the fish tank.

  9. reduce the nitrate level

    Reducing the level of nitrate present in the fish tank is one effective way to stop the brown algae from showing their ugly heads. This can be done by putting a few drops of vodka in the water. Be careful in administering this method as an excess amount of vodka can be harmful to fish health.

Prevent brown algae from developing in your fish tank.

Different ways in which you can brown algae or Diatoms from coming back are:
  1. excess food

    Don't overfeed your fish. I know you love them and you want them to be big but overfeeding them will only lead to wastage as fish cannot consume much food. This excess food settles in the substrate of the tank and will later become nitrates that help the algae to grow.

  2. filtration

    Double on the filtration and use the right filter while at it. If you want healthy, happy fish, adequate filtration is important to keep brown algae at arm's length. Not only that, ensure constant cleaning of the filters to ensure the free flow of clean, good water.

  3. Consistent water flows

    One thing brown algae love is stagnant water. Considering that they can't swim, an adequate flow of water means they won't be able to clump together and become a nuisance to the habitat.

  4. remove many waste or fish poops

    Ensure the aquarium substrate is not carpeted with fish poops, dead fish or waste. As earlier stated. Any of these will increase the nitrates level, thereby, increasing the risk of brown algae.

Video Introduction


Brown algae invasion is one of the many things that discourage fish breeders on their journey. However, practicing cleanliness will be of great help both in getting rid of or preventing algae in your fish tank. With these strategies and methods, you can put things back in shape. This is how to get rid of brown algae in your fish tank.

Affiliate links & Images from Amazon Product Advertising API. Last update on 2020-08-05.

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