Should one start a marine tank with Fish Only (FO), or what's been now popularly called Fish Only with LiveRock (FOWLR) or Fish, with the addition of some invertebrates later on, such as shrimp, crabs, starfish, etc. or do I establish a Reef?

Some of the material in this chapter might be a repitition from the previous chapter. However, I feel its important to emphasize the principles under which aquarium systems are set up, and a lot of the mythinformation being posted, that is highly erroneous.

I will say at this point, IMO, there are only two types of marine systems. Any system that utilizes organisms that establishes denitrification irregardless of the life forms being kept, is a Reef. Any system ONLY based on biological filtration utilzing principles involving aerobic nitrification exclusively, is NOT a Reef. Systems that purport in utilizing aspects of both systems, where both nitrification and denitrification is occuring, IMO, is also NOT a Reef. In my definition, the whole purpose of a Reef, is the implementation of known principles that brings about 'natural' processes that leads to denitrification, the total and complete biological degradation of ammonia, into harmless components and constituents.

Nitrification only stops before the last stage, the production of nitrate and not its elimination, which is denitrification. That's as simple a definition as I can find.

Many questions exist at this point, in the minds of many entering this hobby. Initially aquarium keeping was limited to keeping animals in fresh water, which is easily replenished. The very first attempts to keep Marine Life in aquariums had to rely on a source of SeaWater to maintain these life forms. Analysis of the constituents of Natural Sea Water (NSW) showed a mixture of elements and compounds, various salts and ions of an extremely complex nature. Before marine life could be kept in home aquarias, a synthetic salt mix had to be made that duplicates the constituents of NSW. This is a fine art, that has progressed over many years, until reliable and stable mixtures has been made widely available.

Now that it was possible to approximate NSW in an aquarium, along came the intoduction of marine life forms. Fortunately, there existed much research and scientific data concerning the keeping of FW life, with the nature of the Nitrogen Cycle, and the basic requirements of all aquatic life, Oxygen, Food, and waste management. What distinguishes the various marine systems, is the way waste management is accomplished.

FO systems use the time honored systems originally used with FW, Undergravel Filters, (UGF's), Canister Filters, Hang-On Bio Filters, and WetDry's w/bio balls in a sump. The latest development is the removal of the UGF from inside the aquarium, into a modified canister, where water is forced through some substrate material, now known as a Fluidized Bed Filter.

These all essentially do the same job, powered by devices that move water, which oxygenates the water by exposing it to air, collects wastes in the water, and passes this water through some media, where bacteria proliferate that consume the by-products (wastes) of captive aquatic life. All these devices accomplish one purpose, the reduction of wastes (ammonia) to nitrate. The broad catagory of waste management is based on principles of aerobic bacterial activity, aerobic meaning in the presence of oxygen. Further investigations, following the futile attempts of keeping marine life forms, especially the broad class of species known as invertebrates, discovered that they, for the most part, were unable to adapt to captivity due to their intolerance for nitrate. Only those facilities that had access to NSW managed to keep invertebrates in aquarias.

This led to research by the scientific community into processes that consumed nitrate. Since nitrate does not exist in any appreciable measureable amounts in NSW, scientists started investigating how, what, and where, are nitrates being consumed, as aerobically based biological filtration occurs in nature, so nitrate is being produced. One essential nutrient of all aquatic plant life are nitrogenous compounds, so they must exist in the ocean as well.

This has led to the discovery of another strain of bacteria known collectively as anaerobes, those that live in the absence of oxygen. As far as scientific knowledge of these bacteria is concerned, their existence has been known for a long time. The discovery of bacteria that consume nitrate is relatively newer, at least to hobbyists, and they are classified as facultative anaerobes, bacteria that live in both the presence of, and absence of oxygen, however, in absence of oxygen and presence of nitrate, they consume nitrate, along with other nutrients, including nitrite and carbon dioxide, and further reduce nitrate into harmless oxides of nitrogen and nitrogen gas. This process is known as denitrification.

These bacteria had been found existing almost in all areas of the ocean floor, as well as on land, but, for our purposes, mainly in two areas of the ocean, within the inner regions of the rocks that make up the bases of coral reefs, and within the deeper layers of the ocean floor adjoining coral reefs. For our purposes as SW aquarists, we are primarily interested in what can be reproduced in our aquariums.

Thanks to the investigations of many people working in both the scientific community and aquariology (they are also hobbyists!), these discoveries are now, for the most part, freely available to the home marine aquarist.

The first discoveries of denitrification process applied to home aquariums, came from experiments utilizing what's known today as LiveRock. Aquariums only utilizing LiveRock and Protein Skimming, without any substrate materials, was dubbed the Berlin System, highly successful in the reduction or elimination of nitrate, in strictly invertebrate keeping systems. Problems arose when systems were overloaded, as the denitrification capacity of LiveRock was found to be limited.

In addition to the discovery of the dentrification properties of LiveRock, came the discovery of denitrification in sand beds of the ocean. The problem was in the difficulty of re-creating the conditions of sandbeds in aquariums, because in the ocean, substrates can be up to several feet in depth. Suffice is it to say, that the first artificially constructed and successful denitrifying system was invented by Dr. Jean Jaubert, working for the University of Nice and in conjunction with the Monaco Aquarium. Dr. Jaubert's invention utilized a barrier, acually sometimes two, to simulate the deeper anoxic zones needed for facultative anaerobes, and to keep livesand creatures out of these zones, was dubbed here in this country, as the NNR/Plenum system by Bob Goemans, the leading proponent of Plenum systems in the U.S. As previously stated, new discoveries in sandbed construction has made Plenums unnecessary, by simply making the DSB deeper and stratifying the bed in differing layers of dissimilar grains of aragonite and a layer of LiveSand. The two main components of denitrification requires basically two ingredients, a denitrifying substrate, known now as a DSB, innoculated with LiveSand and LiveRock, those mineralized structures taken from the ocean, where anaerobically bacteria naturally exist.

One more point needs clarification. The term LiveSand refers to material taken directly from the ocean, with all sorts of animals, living in sandbeds, that process nutrients and wastes. Their function in an aquarium is to keep the uppermost layers of our DSB mixed and viable so that nitrifying bacterial colonies can form to consume the ammonia as a result of their biological activity as well as nitrogenous wastes being produced by the inhabitants of our aquarium. A sandbed will not become "Live" just because you have LiveRock in your tank. Its a specific assortment of creatures collectively known as detrivores, and they do not come from LiveRock, but directly from the ocean's substrates.

For the beginner, or even more advanced marine aquarist, a further understanding of the chemistry of nitrification and denitrification processes is outside the scope of my web-site, as there are other better qualified authors, trained in the disciplines of marine biology and chemistry, for those who want a better explanation. Suffice it to say, that a basic understanding of the principles involved, allows one to make an intelligent decision, based on factual and confirmed information, rather then from dubious sources, and in some cases, whose only basic purpose for existence is financial gain.

Now I am not opposed to people making a living or a profit, but am opposed when they publish information contrary to what has been scientifically discovered, on commercial web-sites, which have the weight of authority, but are totally misleading or erroneous.

So we come down to the decision making process, do we only want fish, or do we also want invertebrates? If we decide to only want fish, but still want denitrification, we opt for that FOWLR category, with or without a DSB. What really distingushes the two systems is, a Reef is established for primarily keeping invertebrates, where nitrate reduction is of the utmost importance, with or without fish, who must be basically harmless to invertebrate life, since many fish species consume the life forms living on reefs and in sand beds.��

On the other hand, those who wish to concentrate on fish, where nitrate reduction is not as critical as with invertebrates, do not necessarily need a Reef. Nitrate reduction is easily realized with just regular water changes. The limiting factor between a Reef/ FOWLR and pure FO systems, is in the area of disease/parasite management and treatment, because for the most part, fish cannot be successfully treated for diseases/parasites when invertebrates or denitrifying bacteria exists, without some detrimental or disasterous consequences.

In this authors experiences and investigations, much of which is admittedly based purely on anecdotal evidence, as reported by many aquarists on discussion groups, there is truly no consistent or reliable Reef-Safe treatment or medication, for parasites or diseases of fish, without some harm occuring to other life forms. On many occasions, this is not readily apparent at the onset, because of the nature and life cycle of certain parasites, whose symptoms seem to disappear, only to re-occur, after everything seemed to be fine.

For every case where the medication or treatment regimen was reported as being 'successful', there is a corresponding number of reports of having disasterous results. Those who insist on keeping fish with invertebrates, or having denitrification, along with fish, MUST, quarantine all newly acquired fish in a separate aquarium for 3 weeks minimum, to avoid any possible contamination or introduction of disease or parasites to one's main established aquarium, and the disasterous results, in many cases, sure to follow. Its even advisable to quarantine additions of LiveRock or sessile invertebrates, such as anemones or corals, that can and do harbor the cystic stages of many parasites.

When one follows the recommendations or advise of well-meaning, but poorly informed or read individuals, without some scientific justification based on real hard evidence or facts, one should be very cautious, although one individual may have had some success using a particular regimen or treatment, does not mean it will work for anyone else, and in someone else's aquarium. Anecdotal evidence of success, with various forms of treatment is widespread, especially prevalent on discussion groups. My advice is to consult the literature, and see what people in more scientific disciplines have reported, as being safe and effective. This is still a very new area of discovery, especially in reef systems, so a healthy sketicism is needed, especially when old treatment regimens are resurrected, that had been long discarded by the scientific communty as being unrealistic or unfounded.

With the demise of the popularity of the UGF, caution must be advised when constructing substrates, where a DSB is not desired or feasible. One of the dangers noted with deeper beds, without either, livesand creatures, or sand burrowers or stirrers, is the formation of pockets of sulfur consuming bacteria, coming when wastes and excess foods migrate in the deeper reaches of the substrate, which easily becomes anoxic, because of poor current flow. This situation, not unfamiliar to many aquarists, has resulted in the formation of hydrogen sulfide, characterized by dark or black areas that can be observed through the transparent walls of the aquarium. The liberation of this gas, noted by its characteristic odor of 'rotten eggs' has easily wiped out whole aquarium populations.

Several false notions have been put forth, that hydrogen sulfide is an intermediatory state between nitrification and denitrification. Nothing could be further from the facts, because of the differing types of bacteria residing and forming under various conditions.

For our purposes, bacteria fall into four categories, those that are aerobes or anaerobes, and those that are facultative or obligate. Obligatory aerobic bacteria only exist under specific conditions, such as aquarium nitrifying bacteria, especially Nitrosomonas and Nitrobacter sp. who cannot exist without oxygen. These are obligatory aerobes. There are other bacteria that are facultative, and can exist with or without oxygen. There are also facultative anaerobes, that likewise can exist with or without oxygen. For our purposes, the discussion of various types are limited to the ones useful to us. There are other facultative anaerobes, such as Thisbacilles, that respire sulfur, and who generate hydrogen sulfide, as a result of processing organic matter rich in sulfur and phosphates, as decaying fish wastes and putrifying excess foods. How else would they form, unless they exist previously to putrification processes? Substrates are rich in many forms and types of bacteria. We only attempt to cultivate those that are useful to us, without the knowledge that others do exist, that under certain conditions, become quite detrimental to our systems. You see not all anoxic conditions are the same, nor do they produce the same results. This has led to erroneous conclusions, especially about questioning the feasibility of 'natural' denitrifying sand beds. By processing animals wastes and excess foods, livesand creatures prevent putrification, that allows the proliferation of bacteria that form hydrogen sulfide. Obviously these are also facultative, but do not become active until both an anoxic and putrifying stage exists. The fact that both processes, dentrification and hydrogenization of sulfur, can and does exist simultaneously, especially in poorly constructed sand beds, has led, not only to the mistaken notion that sulfurization is an intermediatory stage leading to denitrification, but to suspicions of the efficacy of the DSB system.

Plenums have also thus been criticized, for being generators of conditions that leads to putrification, and to the production of hydrogen sulfide and complete tank wipeouts. This has also led to the demise of plenum based NNR systems.

Unfortunately, in the case of plenums, this is true, and is their worst characterizations, which seem over time, to allow not only the proliferation of denitrifyers, but also sulfurizers, by defects in design and construction of the plenum, and in the nature of plenum based systems. However, many aquarists, and even commercial establishment, have reported long term success in systems incorporating plenum systems.

This inconsistency has led to the abandonment of plenum systems amongst many advanced aquarists, as well as many scientists working in the hobbyist fields, in favor of 'natural' based DSB systems, which allows the free migration of livesand creatures, and reduces areas where putrification and resultant hydrogenization of sulfur can exist.

Modern methodologies do not criticize a plenum base system as ineffective when set up properly, only that its unnecessary and overly complicated, when a far easier and 'natural' methodology exists constructing a DSB. As you can see the decision to be made, as far as which system to utilize, needs to be carefully thought out, because in many cases, the wrong decision can be very costly, not only in the moneys spent, but in the lives of our animals.