Brown Algae

What is Brown or Golden Algae?

Referred to as a microalgae, brown or golden algae is actually not an algae at all, but diatoms. What you are actually seeing in your tank are diatom skeletons, all linked together. It can appear as a simple dusting on the tank walls and substrate surfaces, or it can turn into a massive growth that covers just about everything in the tank. This type of algae outbreak typically occurs when a tank is just completing or has finished the nitrogen cycling process, new live rock is introduced, as the curing process can add nutrients when some organisms on the rock dies off, or tank maintenance has been neglected.
It is a normal occurrence, as diatoms are one of the first to appear in the chain when the tank conditions are conducive for algae growth, and is usually a precursor to other forms of desirable and undesirable nuisance type green macroalgae.

What Makes Diatoms Grow and Solutions For Eliminating This Problem

It is suggested that you don't try to put all of these solutions into action at one time, because if you do, when to problem subsides you'll never really know "exactly" 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, i n 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.
    • Solutions: Only use bulbs that are designed for aquarium use, paying close attention to their spectral output; don't bombard the tank with an over abundance of light, follow the basic wattage rule of thumb; run the lights 8 to 9 hours a day.
  • Nutrients: Diatoms are most responsive to silca/silicates, but DOCs (Dissolved Organic Compounds), nitrates, and phosphates are food sources as well.
    • Silicates are most often introduced into aquariums by means of using unfiltered fresh tap water, the wrong kind of sand or substrate material, and through sea salt mixes that contain a higher than normal concentration of this element.
      • Solutions: Use RO/DI filtered make-up water, an aragonite type sand or substrate source, and a high quality sea salt mix.
    • Phosphates (PO4) 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. Allowing excess DOCs to accumulate in an aquarium in turn gives rise to nitrate (NO3) problems. However, nitrates can also be introduced in the same manner as phosphates, and because it is the final byproduct produced in the nitrogen cycling process, it can naturally build to high levels due the lack of proper aquarium maintenance care. As mentioned earlier, another contributor to DOC/nitrate problems is when new live rock is introduced, as the curing process can add nutrients when some organisms on the rock dies off.
        • Solutions: Practice good aquarium maintenance care routines! This includes keeping the substrate clean, cutting back on feedings, regularly rinsing, rejuvenating or changing any type of prefilerting or absorbing materials (such as filter flosses, cartridges, bio wheels, sponges and carbon), performing regular partial water changes, and for DOCs in particular, adding a protein skimmer. For those with systems that have been running for some time and use wet/dry trickle type filters, the bio media in them, especially bio balls, are real nitrate factories, and therefore should carefully be rinsed and cleaned periodically.
        • Add some good diatom eating Trochus and Astraea snails, a fish, such as a Kole Tang, Potter's or Flame Angelfish, and to help keep the aquarium bottom clean and tidy, some algae/detritus eating hermit crabs, a tank friendly true crab, shrimp, or other type of tank janitors. Of course you DON'T want to add ALL of these critters, just choose on or two of these options. In our photos, the clear or white looking patchy area at the bottom of the diatom algae is from where a small true crab in our tank ate the algae off the glass that it could reach.
        • When adding live rock, take the time to cure it properly.
        • Important Note: If your tank is still cycling, DO NOT add any new animals, do ANY water changes, or perform ANY MAJOR substrate or filter cleaning tasks, other than to change dirty prefiltering materials and/or to QUICK siphon stuff off the bottom, until the tank has COMPLETELY FINISHED cycling. The unsightly brown algae can easily be removed temporarily from the walls of the aquarium by using an algae scraper, sponge or magnet, and scrubbed off the substrate and rocks with a toothbrush, where it can then be removed from the water through mechanical filtration, such as by adding a hang-on-tank canister filter (read product reviews and compare prices), and larger floating pieces can be removed with a net, turkey baster, or by light siphoning.
        • Carbon Dioxide (CO2): Low water flow or movement throughout the aquarium produces carbon dioxide (CO2), which algae consume.
          • Solutions: Depending on the size of the aquarium add a powerhead or two, install a wavemaker or surge device and/or increase the flow rate or efficiency of the filtration system.
          •  Solutions for this situation are to add another 
        By putting into action any of these solutions, as the growth sources are being eliminated you should see a "gradual" decrease in the growth of the slime algae. In the meantime, while you determine and correct the actual cause underlying the problem, the unsightly algae can manually be removed as mentioned above.

        One final interesting note is that because diatoms "consume" nitrates, often when aquarists perform nitrate tests, the readings come up as normal. Don't be deceived. If you were to remove the diatom algae temporarily before putting into action any of the above solutions, in all likelihood you will see a rise in the nitrate levels in the aquarium. It's like a catch 22. The nitrates have actually been there all along, but unreadable as the algae is feeding on it, therefore the nitrates "appear" to be in check. This applies to many other forms of algae as well!

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