Silicates

• The single most common cause of brown algae formation is silicates. Silicates come from tap water and can also be introduced into an aquarium from the use of marine salt. The easiest way to control silicates permanently is using a reverse osmosis filtration system. This kind of filtration removes all dissolved silicates and organic particulates from tank water.
  
  

Nitrates

• Overfeeding fish can quickly lead to a nitrate spike, which promotes algae growth.Comstock/Comstock/Getty Images
  
  A nitrate spike is a common side effect of overfeeding in an aquarium. Test strips can be purchased to check nitrate levels in water. If nitrates are only slightly out of line, water conditioners can be used to easily remedy the problem. For a more long-term solution, protein skimmers are a better method of nitrate control. Protein skimmers remove proteins in the water before they can promote algae growth.
  
  

Direct Sunlight

• Direct sunlight is a very easy way to spur brown algae growth. Just like any other type of algae, brown algae uses photosynthesis to convert sunlight into energy. If an aquarium is in direct sunlight the best option is to relocate it to an area with less light.
  
  

Chemical Filtration

• Chemical filter medias remove organic material from aquarium water. This kind of filter has the advantage of being far less expensive than reverse osmosis setups. However, if the source water used to fill an aquarium is the cause of excess nutrients, reverse osmosis filtration may be the only permanent solution.