Activated carbon is perhaps the most common type of chemical filter. It is generally placed in an area of higher flow so that the water passes through the medium allowing it to capture organic elements and bond with other elements. This can be accomplished by either putting the carbon in the path of the drain to the sump, adding a canister filter to the system and using it to periodically filter with carbon, or, as we are doing with Tank 1.0, using a small HOB filter to put the carbon in.

The literature on the internet varied considerably on the frequency of replacement, but as carbon traps the yellowing agents in the water, when the water shifts towards yellow once again, it is generally a good indication that the carbon should be replaced. Carbon is also highly porous and will be settled by both nitrifying and denitrifying bacteria. Depending on the quantity of carbon being used in the aquarium, one may want to replace the medium in parts rinsing the remaining with fresh seawater.

Foam fractitioning devices are commonly known as skimmers. They work by creating a column of fine bubbles to which organics and proteins will stick and are removed before they can convert into nitrates. The column of bubbles rise up to a collection cup at the top of the skimmer which is then emptied periodically and cleaned.  Skimmers come in several varieties, co current, counter current, and recirculating.

The co-current design uses an airstone, or something similar, to create the column of bubbles and the water flows along the same path with the bubbles. The counter-current design is similar however the air is injected against the stream of water to the same effect and has longer contact with the water before rising to the collection chamber. Finally a recirculating skimmer will cycle water through the column of bubbles several times before sending it back to the tank or sump. The counter-current design is considered more efficient than the co-current. Skimmers are considered an essential part of a reef aquarium.

Absorption filters are chemical packs designed to extract a given substance from the water. They are often used to do things such as lower the phosphate levels (PhosBan). These filters are useful for single tasks and make a good additition to the reef aquarists toolbox.

Ozone is a naturally occuring gas found in the upper atmosphere. It is also an exceptional oxidant. When used in the reef aquarium it is capable of breaking down organics and nitrates. At higher levels, however, it is capable of causing damage to corals and fish.

Ozone is typically administered by mixing it with the air in the foam fractitioner, and then running the output of the skimmer through activated carbon to remove any remaining elements of ozone or broken down organics. Ozone is an advanced technique and firmly outside of the scope of Tank 1.0.

Out of the chemical filtration methods for a reef aquarium, Tank 1.0 will be using a protein skimmer, we selected an Aqua C Remora for ~$170 from an online vendor, and activated carbon. Some PhosBan packs will be obtained and used if necessary to combat high phosphates assuming frequent water changes are insufficient to handle them directly.

Thanks again and we hope you come back and learn more about the reef aquarium.