This is a revised editorial from one of my previous articles last year. The use of carbon in saltwater aquariums has been a very controversial subject whenever you search for the topic online. There are so many conflicting debates with tank owners on whether or not to use this type of media. In turn, this raises the question if carbon is good or bad for the overall health of a saltwater tank. As an aquarium hobbyist, as well as being someone who took many biology and chemistry courses, I am going to help explain what carbon does when it reacts with water.

What to Know About Carbon in Saltwater Tanks

To start things off, carbon is NOT harmful to saltwater species. When using a mechanical filter for saltwater tanks, the water passes through the filter and media just like it would with any other type of setup. However, it does not strip away any salinity in the water, or if it does then it is such a minuscule amount that it cannot be seen on a refractometer when tested. When water passes through the filtration, the ammonia, nitrites, nitrates, and any other organic waste is being trapped in the filtration pad. Not only that but the carbon is then purifying the water when filtered back into the tank, and gives the water a very pristine look. I have used carbon filtration in two out of four of my aquariums (one of them being my most recent aquarium), and I have had absolutely no detrimental effects with doing so. Not only has my tank flourished with using carbon, but the water is so clear that it looks as if the fish are floating in air. I also have anemones in my aquarium, to which they have have no issues whatsoever with the introduction of carbon.

How carbon filtration works microscopically

How to Use Carbon in Your Aquarium

Carbon is used in the same way as it is for a freshwater aquarium. There is not really any difference on how to set this up. If you wish to add on a hang on the back filter (HOB), then the filter pad or media bag can be stored inside of the filtration device itself. A media bag can also be placed in overflows or refugiums in one of the designated storage departments. Treat this setup like you would any other tank. It does not have to be difficult or complex. Usually people like to over-think how they should map out their aquarium hardware or filtration, but make it easy on yourself. If you run a sump or refugium, then by all means put the carbon in the designated chambers instead of rigging an external filtration system. If you run a HOB, the filter pad should not be seen as a useless piece of equipment. I’ve heard many people say that to just throw it out if you use a hang on the back filter, but I would like to implore you to do otherwise. Keep it in the filter, there is absolutely no harm to the aquatic life by doing this. The one thing I will say to not run a carbon filter for is if you are dosing for disease or illness. Instead of steering away from carbon, though, you can simply remove the filter pad during medication intervals and reapply it later.


Cleaning and Maintenance

The one main thing you will need to do for maintenance is rinse the filter pad off in excess aquarium water or distilled water when it needs to be cleaned. Do not use tap water!!! I have seen so many people run their filtration pads through the tap and then later ask why their fish have died. Rinsing the filter pads off in tap water traps chlorine inside of the pad itself, and then expels it back into the aquarium which poisons the fish. As many of you know, chlorine should never be present in any aquarium setting for this exact reason. Aside from that, filtration pads should be changed out once they begin to erode, turn a dark brown or lose their effect. For me, they can last close to a quarter of a year with moderate feeding and no overstocking of fish. As long as you are conscious about what you are doing then this method of carbon use is perfectly healthy for your fish and the longevity of your aquarium.