Choosing a Filtration System for Your Saltwater Aquarium

New 40 gallon long tank
jprime84/Flickr/CC BY-ND 2.0

With such a wide variety of filtration methods to choose from, saltwater aquarium filter selection can be mind-boggling. If your tank is already equipped with a built-in filtration system (ex., Eclipse, SeaClear and Perfecto Biowheel Ensemble), your problem is solved, unless you want to modify or add on to it. So, how do you pick one? Let's start with the basics.

There are 3 basic types of filtration in saltwater (or freshwater, for that matter) aquariums, all of which play a part in or enhance the Biological/Nitrogen Cycling Process:, which is every aquarium's primary filter. They are Biological (B), Mechanical (M) and Chemical (C). Some filters are capable of performing more than one task.

Biological which, with the aid of bacteria (nitrobacter & nitrosomona) convert ammonia into nitrate, then into nitrate via these filter types:

  • Granular Activated Carbon (GAC) or pelletized carbon can be used not only for chemical filtration but because of the huge amount of surface area for the volume, due to the porosity of the carbon, makes an excellent platform for a biological filter. This large surface area is where the "good" bacteria can grow and process the ammonia and nitrites that passes by the bacteria. (C, B)
  • Wet-Dry Trickle Filters have the flexibility to be used for many purposes including mechanical, chemical and biological filtration. Wet-dry Trickle Filters are also great for do-it-yourself filtration systems. (M, C, B)
  • Live Rock Filtration & Berlin Systems are the original "bare-bones" natural filtration systems that have been around for eons. Live rock filters are about as foolproof as you can get and they work great. (B)
  • Using Live Sand / Live Sand & Jaubert/Plenums are basic filters that work great but have some limitations. (B, NNR)
  • Undergravel Filters were in vogue for quite a while until the wet/dry, live sand and live rock filters became popular. While the UGF's are still used for a number of applications they have for the most part been abandoned due to their reputation for being high maintenance and for producing a lot of nitrates. (M, B)

2) Mechanical filters, which physically remove both dissolved and particulate material from the aquarium water column.

  • Granular Activated Carbon (GAC) (C, B)
  • Canister Filters are compact, multi-purpose filters which can be adapted for a number of purposes. (M, C, B)
  • Protein Skimmers utilize, of all things, bubbles, to remove D.O.C.'s and proteins from aquarium water before they have to be processed by the biological filter in an aquarium system. (M)
  • Undergravel Filters trap particulate matter in an aquarium by pulling the water through coarse sand, crushed coral or aragonite. (M, B)

3) Chemical filters which remove toxins through chemical reaction or adsorption.

  • Granular Activated Carbon (GAC) or pelletized activated carbon remove chemical toxins and a number of other substances such as medications and copper treatments from aquarium water. (C, B)
  • Canister Filters have a number of chambers which loaded with a wide variety of filtration products such as ceramic rings, granular or pelletized carbon and even porous packets which contain specialized materials to remove nitrates, phosphates and a number of other toxins from aquarium water. (M, C, B)
  • Mangrove Plants (NNR - Natural Nitrate Reduction method) are truly amazing. These plants strain freshwater out of saltwater and filter out toxins such as nitrates and phosphates.

There are a number of well-designed multi-functional canister filters on the market today that may fulfill your needs.

For more insight on the many ways filtration systems are utilized, browse the Tank Photo Resources. These are links to personal saltwater Web sites where aquarists' provide all kinds of detailed information about their aquariums, including their filtration set ups.