Brown Algae: Causes and Solutions
Veterinary & Aquatic Services Department, Drs. Foster & Smith

Q. I'm having problems with brown algae in my fish-only marine aquarium. I do regular water changes, but with no results. What else can I do to get rid of the brown algae?
A. A number of factors encourage the aggressive growth of brown algae, but the presence of excess nutrients, including silicate, is the number one factor. Excess nutrients most commonly come from overfeeding.

Depending on what part of the nation you live in, your source water may contain varying levels of chloramine, nitrate, phosphate, silicate, and other algal nutrients. Test your source water to see if these chemical nutrients are present. Test for ammonia, nitrite, and nitrate using a master test kit. A silicate test kit and a phosphate test kit can be purchased individually. If your source water reads positive for these chemicals there are several steps you can take to remedy the situation:

  • Increase the number of water changes.

  • Protein skimmers: These remove dissolved proteins in your aquarium before they have a chance to break down.

  • Chemical filter media: When placed in your filter, chemical filter media, such as Poly Filter and Phosphate + Silicate Magnet, will remove silicates, phosphate and organic waste materials.

  • Reverse osmosis (RO) units: These water-purifying units will remove chemical nutrients directly from your source water.

However, if the introduction of these nutrients stems directly from your source water, the algae will have a constant nutrient source, no matter how many water changes you may perform or how efficient the protein skimmer or the chemical media may be. Thus, an RO unit will be your only permanent solution.

   Click here for the web viewable version of this article.

Click here to email this article to a friend.

Copyright © 1997-2016, Foster & Smith, Inc. All Rights Reserved.
Reprinted from