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Red Slime Algae (Cyanobacteria) Description

What Is Red Slime Algae?

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Red Slime Algae

Red Slime Algae

Stan Hauter
Red slime algae is actually not a "true" algae at all, but classified as a cyanobacteria. Often considered to be the evolutionary link between bacteria and algae, cyanobacteria are one of the oldest forms of life on earth and date back at least 3.5 billion years. These organisms produce oxygen as a byproduct of photosynthesis, and scientists believe that if it weren't for this microscopic organism, there would be no blue skies on Earth.

Commonly referred to as "red slime" algae, the name cyanobacteria literally means "blue-green" algae. Despite the naming, only about half of these organisms are actually blue-green in color. Most forms found in saltwater are other colors, ranging from blackish green to blue-green, from orange-yellow to reddish-brown, and often appear deep purple to fully black in color. Starting out as small patches, it spreads out from there as a mat of sheeting covering.

What Makes Slime Algae Grow and Solutions For Eliminating This Problem

We suggest that you don't try to put all of these solutions into action at one time, because if you do, when the problem subsides you'll never really know where the problem was coming from and which solution worked to fix it. Start with one solution and see what results you get, and if that one doesn't work, try another one, and so on, until the problem is resolved. Now, in order for all forms of algae to grow, they require only two things; light and nutrients.

  • Lighting: The use of improper bulbs, lack of maintenance, and extended lighting hours are contributors that can lead to all sorts of algae problems. While these organisms do well in the 665 to 680 nanometer (nm) wavelength range, they are quite active bewteen the 560 and 620 nm range as well.
    • Solutions: Only use bulbs that are designed for aquarium use, run the lights 8 to 9 hours a day, and following the basic wattage rule of thumb, try different types of bulbs to increase the intensity and the spectral qualities of the light in the aquarium, particularly when it comes to any type of full-spectrum or color enhancing tubes being used.
  • Nutrients: Phosphates (PO4), DOCs (Dissolved Organic Compounds), and nitrates (NO3) are primary nutrient food sources for red and other slime algae.
    • Phosphates (PO 4 ) are commonly introduced into aquariums by means of using unfiltered fresh tap water, and through many aquarium products that may contain higher than normal concentrations of this element, such as sea salt mixes, activated carbon, KH buffers, foods, and many other sources. Also, for established reef tanks the long-term use of kalkwasser precipitates phosphates out of the water, and these phosphate based compounds can settle on and in the live rock and substrate.
      • Solutions: Use RO/DI filtered make-up water, a high quality sea salt mix, and be aware of the elements contained in other common aquarium products you may be using.

Red Slime Algae Causes & Cures

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