Managing dissolved nutrients–especially ammonia, nitrite and nitrate–is among the major tasks of reef aquarium husbandry. Accomplishing this can be easy or difficult, cheap or expensive, depending upon how you go about it. And there are lots of ways an aquarist can go about this job. This ranges from operating planted refugia to performing massive regular water changes to chemical filtration or, most often, at least one form of biological filtration.
Just looking at biological filters, there are many approaches that one could take and media that one could use. The general idea, though, is that (1) the medium provides as much surface area per unit volume as possible and (2) the culture environment is highly aerobic for nitrifying bacteria and completely anaerobic for denitrifying bacteria. In both of these respects, a well-studied ceramic-based biomedium sold as MarinePure™ totally excels.
Room to grow
Too often, when shopping for biomedia, aquarium hobbyists get it all wrong. Generally, they have the filter (i.e. some specific amount of space to fill) before they acquire the media. A natural tendency is to attempt to fill the media chamber for the lowest possible price. This is a mistake, as different types of biological filter media have very different surface area/volume ratios.
Compare, for example, MarinePure to various other widely used materials. The SA/vol of an 8x8x4 block of MarinePure is approximately 139,800 ft2/ft3. Various other ceramic media are usually around 20,000 ft2/ft3. Super-porous feather rock is only around 19,000ft2/ft3. And normal plastic bioballs? Like, a measly 100 ft2/ft3.
MarinePure owes its incredibly high SA ratio to its porosity. Its unusual, specially engineered structure creates a highly open porosity (80-90% ) and an extensive surface area (1.3-1.7 m2/g). This also makes it incredibly lightweight; this material features a bulk density of only 0.3-0.5 g/cc!
This means that you can potentially maintain much, much denser colonies of beneficial bacteria than with other, “conventional” media. Remember this while pricing different materials (or sizing your next biofilter)! When comparing SA ratios for a predetermined bioload, differences in required filter chamber size between MarinePure and other media differ by factors in the 10s or even 100s.
Nitrifying bacteria, while of diverse lineage, overwhelmingly are obligately aerobic organisms. They cannot survive, much less perform nitrification, if they are suffocating. Flow-through in a biofilter must be high enough to
deliver sufficient oxygen to the medium. Thus, one of the dilemmas of establishing a biofilter has always been centered around packing as much biomedia into the chamber as possible without impeding flow or creating dead areas.
MarinePure’s high porosity allows water to pass through it quite easily in active (i.e. flow-through) filter systems. In fact, water can trickle through (not just over) the material when used in wet/dry applications.
On the other hand, this versatile material is equally suited to host denitrifying bacteria (which are generally obligately anaerobic) when used in passive systems. Whereas plastic media such as bioballs provide no inner, anaerobic microhabitat at all, MarinePure (especially its inner core) provides ample anoxic living space.
In most cases, aquarists use strong but passive flow in their biomedia chambers. This works great with MarinePure; nitrification occurs over the surface, while denitrification occurs deeply within.
In their places
MarinePure is available in a number of different shapes and sizes (big and small blocks (“plates”), spheres, and chunks (“rocks”)). Different types are best used for specific purposes.
Because the rocks look and function very much live rock, they may be hidden within the hardscape to enhance nitrification and/or nitrification, depending upon water flow characteristics. For example, they work well as base rock when placed at the bottom rear of the reef structure.
MarinePure GEMS, cubes or spheres are great for nitrification. They fit snugly to fill any sort of biofilter chamber, including canister or hang-on-the-back style filters. Installing a mechanical filter in the stage preceding biofiltration will increase the efficiency of MarinePure, as it reduces the amount of particulates that can clog the medium’s tiny pores. To promote colonization of the Biomedium by desirable microbes, saturate it with a live liquid nitrifying bacterial inoculant such as Fritz TurboStart 900 just prior to final placement.
MarinePure blocks are likewise great for denitrification. These are best placed at the bottom of the sump or refugium; for this particular purpose, the areas of weakest water flow are ideal. To promote colonization of the biomedium by desirable microbes, saturate it with a live liquid denitrifying bacterial inoculant such as Hydrospace PNS ProBio just prior to final placement.
One nice little “extra” about MarinePure is that it provides a fantastic home for tiny animals such as copepods.
Whether used for nitrification, denitrification or both, we advise against disturbing an established biofilter unless absolutely required (e.g. to relocate a tank), as it can disrupt/harm the bacterial community. Thankfully, this medium does not need to be cleaned over time. But when it does need to be moved, the blocks are of course easily picked up whole. The loose GEMS or spheres are best kept in a basket; this facilitates handling should the need to move them ever arise. Whenever handling MarinePure (whether while it’s wet or dry), be aware that it is rather brittle (this can be expected of any material that has such a high porosity!). With minimal/careful handling, your MarinePure media will last virtually forever (they are even ozone resistant!) and can provide the perfect home for your microbial colonies indefinitely!