Does UV Filter Kill Brown Algae? {Best Way To Remove Brown Algae?}

Planted aquariums are some of the most beautiful and enjoyable tanks to look at, and the fishy inhabitants obviously love the real deal, but these gorgeous setups can come with some issues, including brown algae.

Brown algae, also known as diatoms, can appear in any aquarium, but the lush environments of planted tanks are especially susceptible to this ugly algae.

Brown algae usually show up at the beginning of tank setup, so is it possible to be a step ahead of growth?

Does UV Filter Kill Brown Algae?

Yes, UV filters will kill free-floating brown algae, but won’t kill algae that are already attached to a surface.

Algae is the bane of many aquarists’ existence, and as such, it has inspired the invention of dozens of algae eliminators. One of the easiest and most convenient algae killers is the UV filter, also known as a UV sterilizer.

Does UV Filter Kill Brown Algae

UV filters can kill brown algae (diatoms) as long as it is free-floating, because UV filters kill the algae in the water as it passes through the filter.

UV filters can’t kill any algae that have already attached to the glass or any other surface.

Most of the time, brown algae disappears on its own as the tank cycles and settles into equilibrium, but things like a nitrogen cycle crash and excessively large water changes can cause brown algae to reappear.

You can combat these algae with UV filters, but you’ll need to pair the filter with manual algae removal to successfully eliminate it without waiting on the tank to stabilize again.

Best Way to Control Brown Algae in Tank

Brown algae are thankfully not one of the more stubborn algae, so with a few changes, you should be able to control it.

You can use some of these methods to control brown algae in your tank:

  • Water changes- Brown algae feed on nitrates and phosphates, and regular water changes help control the amount of these in the tank.
  • Increase filtration- Diatoms need organic matter to survive, and a good filter will get rid of much of this matter.
  • UV Filter- UV filters can remove free-floating brown algae.
  • Manual algae removal- Cleaning brown algae from the glass or other surfaces makes it easier to be disposed of by the filter or killed by a UV filter.
  • Avoid overfeeding- Overfeeding can cause too much organic matter to be present in the tank, causing brown algae.
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How to Prevent Brown Algae From Returning?

To prevent brown algae from returning, you’ll focus on keeping your tank clean, well filtered, and free of excess organic matter.

Brown algae usually disappear once a tank is completely cycled, so it’s important to keep the nitrogen cycle intact. Nitrogen cycle crashes don’t just invite more brown algae, either; they can be devastating to tank livestock.

To make sure the brown algae never returns, make sure you have proper filtration. Good water flow throughout the tank is also helpful, as well as a UV filter for killing any algae before it has a chance to attach to anything.



Hello, I'm Jason. I'm the guy behind I volunteer at my local fish shop and I created this site to offer tips and advice on the fish I care for.

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