Carbon is used to remove a wide variety of contaminants and organic compounds from your aquarium. Most of these are the results of organics breaking down in your water that cause odors and discoloration. It is also fantastic for removing medications and other chemicals/toxins whether they were intentionally added to the tank or not.

The use of carbon will result in crystal clear water for pristine viewing by removing the yellowing pigments. Not only does that mean a better-looking tank, but it also ensures maximum light penetration (optimal PAR) down into your reef.  It can also protect your tank inhabitants from harmful chemicals that are released by corals during times of stress or silent killers such as air fresheners, scented candles, hand soap and lotions, and even some household cleaners.

Types Of Carbon

The two major types of carbon are Bituminous Carbon and Premium ROX 0.8 carbon, each of which is structured differently and has different uses. Bituminous carbon has tiny pores meaning that it is ideal for filtering out smaller molecules like chlorine. While bituminous carbon isn’t the most efficient type of carbon for filtering your entire tank, it is relatively cheap, low dust, and will still get the job done for most applications, especially when targeting medications or chemicals.

ROX carbon is a blend of different carbon sources that has been extruded into pellets. This means that it has a variety of pore sizes and can pull molecules of different sizes out of your water, giving it the largest filtration potential among ALL aquarium carbons. Its commonly used in settings like pharmaceutical labs where contamination standards are extreme. ROX is a bit more pricey, but adds nearly no dust to the water, is great for maximizing your filtration potential and removing odors and colors.

How Much Carbon Do I Need?

BRS Bituminous Aquarium Carbon

  • Start with 1 Tablespoon per 4 gallons of aquarium water
  • Replace once carbon is exhausted (typically 1-2 weeks)

BRS ROX 0.8 Aquarium Carbon

  • Start with 1 tablespoon per 10 gallons of aquarium water
  • Replace once carbon is exhausted (typically 1-2 weeks)

Shop Filter Media

How To Use Carbon

For Use In A Filter Media Bag:

  1. Pour the carbon into the bag and close securely.
  2. Rinse with RO water or place under a faucet until the water runs clear. Do not rub the bag as it will grind the carbon and cause more dust.
  3. Place in a high flow area of the tank or sump to maximize water flow through the carbon.
  4. Change out carbon every 1-2 weeks or once the target contaminant is removed. Carbon should never be left to run longer than 14 days. Changing it out weekly is best.

For Use In A Upflow Media Reactor:

  1. Place carbon in a suitable media reactor.
  2. Place the reactor's return line into a bucket or sink.
  3. Turn on the feed pump to flush the fines/dust from the carbon until the water runs clear.
  4. Install the media reactor on your tank and place the return line appropriately into your sump or filtration.
  5. Reduce the flow through the reactor so the carbon barely tumbles on the surface. Do not allow the material to vigorously tumble.
  6. Change out carbon every 1-2 weeks or once the target contaminant is removed. Carbon should never be left to run longer than 14 days. Changing it out weekly is best.

**Pro Tip: Carbon will exhaust quickly in a marine aquarium, especially in tanks with heavy organics or running medications. It is best to replace carbon every 7 days and only use exactly what your tank needs, anything longer and the carbon is likely not doing any good, and using more than required is wasteful in most scenarios.  To learn more, check out our Top 20 Carbon and Media Reactor Mistakes video in which Ryan and Randy provide you with 20 super helpful tips for using carbon inside a media reactor.