The Best Ways to Remove Brown Algae from the Aquarium.

Brown algae which is also known as diatoms can be very difficult to remove from the aquarium. To make matters worse Brown algae looks terrible and can be harmful to your fish. Brown algae is a unicellular organism that is brown in color it has a bony structure that is primarily composed of silicon nitrate. Brown algae develops in aquariums with high nitrates and sometimes those with high silicon levels. Brown algae can also take over the tank when the lighting is too high or too weak for the aquarium. The best way to remove brown algae is to limit these key factors. Brown algae can be toxic to your aquarium inhabitants and it can also be damaging to the plants (or coral in marine/salt water aquariums) housed in the the tank. Identifying Brown algae is fairly easy usually Brown algae will accumulate over everything including the glass and substrate. Brown algae usually resemble a fine dust ranging from light to deep brown.

Brown algae in a marine aquarium


Listed below are some of the best ways to remove brown algae from the aquarium. Most of these methods aim to cut the nutrient supply for brown algae. Preventing its future growth.

  • One of the best ways to remove brown algae is by physically removing the accumulated brown algae from the aquarium. Use a suction or your hand to remove the algae. The brown algae will spread faster if left in the aquarium and it will be difficult to eradicate.
  • Provide appropriate lighting for not less than eight hours a day. If there are no corals or plants in the aquarium, you can reduce lighting to just 6 hours per day to help in removing the algae.
  • Using filtered water from a RO unit controls the growth of brown algae as this water is free from nitrates and silicates. Check the water from your tap to see if it contains silicates, this is a common cause of brown algae.
  • Nitrate level need to be decreased to control brown algae which can be done by adding a few drops of vodka in the water. Vodka dosing needs to be monitored as it can result in harm to your fish. Nitrates can also be reduced through nitrate absorbing filtrates placed in the filter. Keeping the nitrates low is one of the best ways to remove brown algae and prevent it from showing its ugly head.


  • Cleaning the filters and changing water regularly ensures flow of clean water that is free from silicates and nitrates. Always change the water and clean the aquarium at least twice per week. Clean more if the algae is becoming a problem.
  • Being very careful in marine aquariums to read the label of the salt mix. Be sure to use salt mixtures and rocks that do not have silicate content.
  • Do not offer extra food to the fish. The food that fishes do not consume will just end up as nitrate in the water column. One of the best ways to remove brown algae is by paying close attention at feeding time. Feed slowly for two minutes. Do not let any wasted food sink to the bottom out of sight.  
  • Ensure that the aquarium does not have any loose waste, dying material or it is over stocked. Once again, any of these may increase the likelyhood of nitrates and increase risk of brown algae.

After removing the algae it is imperative to keep a low nitrate environment. This will ensure the brown algae is ‘starved’ and not able to regain growth in the aquarium. If your tap water contains silicates it will be necessary to use RO water during water changes. Brown algae is one of the worst and prevalent types of algae. Getting it under control is difficult but not impossible. The list above outlines just a few ways of containing an outbreak. If you have any added comments or suggestions please feel free to leave them below.

20 thoughts on “The Best Ways to Remove Brown Algae from the Aquarium.”

  1. Episom salt works great also a 1/2 teaspoon per 10 gallon for 1 day a week for 3 weeks works also hydrogen peroxide works but only use in cap fulls per day. Brown algae can also come from drift wood that is not properly clean. Feeding should be on a two day interval add janitors if needed( Cory catfish funnel snails are good they promote airiation to the substrate an they are not plant eaters they only eat algae. Pleco are ok but become aggressive an will eat live bearers an slow moving fish. They do good with algae but slowly eat your live plants. In the wild fish eat once a day an hide the rest of the day. Also lower temp also kills algae …75° an lower 70° higher temp promote growth 76° 89°

    1. Thank you for sharing. I would like to add that Cory cats are not algae eaters. They assist in the prevention of algae growth by scavenging for uneaten food, which is a source that feeds algae. And pleco’s don’t necessarily become aggressive. They look for an area to clean and sometimes that area is the body of another fish. They don’t discriminate. Unfortunately, Pleco’s get HUGE and are filthy little creatures themselves. Shrimp, snails, Siamese algae eaters, and Otocinclus are the preferred choice for removing algae via fish. But make sure any fish you get is compatible with current stock.

    2. Turn lights off! There is conflicting info on the internet about more or less light. I’m telling you – turn off the lights! Algae is a plant, therefore it needs light for photosynthesis.

      1. By the way, Brown algae a nickname because it is similar in appearance. In reality it is not a plant. Its a colony of diatoms. Actually a single celled creature.

    3. I have a small 1 or 2 gallon fish tank…not sure. With 1 betta fish – what or how much epsom salt could I add to the water to get rid of the brown algae?

  2. I think a big one as well depending on the size of the tank is taking the time to try and brush off some off the algae on your plants. It’s tedious but if you are having growing issues and your plants are covered in the stuff then their growth will be reduced

  3. I can not control this ugly brown algae. It grows in the center of my 40 gallon freshwater tank. I have physically removed it by extracting the gravel (several times) and it keeps coming back. Last water change, I used a special filter and it is back. I’m going crazy with this.

  4. I tried no light for 48 hours ….. the brown stuff took off like a bat out of hell .. so sorry but reducing light doesn’t work.
    I have top of the range plant LED light on my tank for 9 hours a day … also doesn’t get rid of brown stuff (not an algae so I’m told)
    I suspect our tank water may be high in silicates (I water change 10-20% twice a week and vacuum up any waste), but don’t know how to test for this – can anyone help on that one?
    Glad to hear that vodka might work as well on the brown stuff as it does on my bad back (internally LOL), but how much for my 100 gallon?

  5. I had this problem
    I tried manually cleaning the aquarium…stones..the decorative items etc repeatedly
    Nothing worked
    I added two small tank cleaner fishes
    In imy aquarium i have only gold fishes
    The tank cleaners cleared up the brown algae (diatoms) within 24 hours
    No more of this prob

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