In my column last month I reviewed how the reefkeeping hobby is filled with seemingly "new" ideas that are periodical and cyclical in nature. Some historical and current trends by which reef aquarists seem to constantly "re-invent" themselves were discussed, and in this article I will detail my thoughts on another such trend, namely, adding vodka to aquariums.

Since some European countries have been instrumental in advances in reef aquarium techniques, there is often a perceived impression that their knowledge and skills are something to be awed. Having seen, visited, and been involved with aquarists in any number of European countries, I can say that the average state of the hobby overseas is similar to what it is in the United States. There are some great aquarists, there are some moderately successful aquarists, there are some struggling aquarists, and there are a slew of people who probably should never have bought the tank in the first place. Europeans also regularly complain about a lack of informative material available in their native language, and periodicals from Britain, Italy, France, Germany, and other countries are similar to those offered here. In other words, there are some articles of value, and some that probably should have been left in the editor's trashcan rather than appearing in print. My initial point in this subject is that just because Europeans have better cheese, bread, and architecture than we do does not necessarily make them omnipotent, or even desirable, as reef aquarium authorities. I might also add that one of the best vodkas, surprisingly, is made right here in my home state of Texas; a gold-medal winning brand named Tito's handmade vodka which, when mixed with fresh-squeezed ruby red grapefruit juice, ice, and a squeeze of ripe Mexican lime, may not be ideal for the reef aquarium, but which does offer some benefit to the aquarist on hot summer nights.

The "Theory" Behind Ethanol Additions to Aquariums

A German magazine recently published an article suggesting and recommending the dosing of ethanol (as vodka) to reef tanks as a carbon source for marine heterotrophic bacteria in order to increase denitrification rates and bacterial biomass production (Mrutzek and Kokott 2004). Further, they claimed that additions cause rapid declines in nitrogen and phosphorus produced by fish, invertebrates, and algal metabolism (ironic, since many aquarium invertebrates and algae are sinks, not sources, for nitrogen and phosphorus). In turn, the bacteria provide a food source for corals and other filter feeders. The method is recommended particularly for those tanks that are highly skimmed (and probably lack particulate material) and which lack sand beds. Tanks with sand beds or other sediment-based systems, they mention, react unusually and may have adverse effects to ethanol additions.

"Experiments" were performed (and I use the term experiment loosely to mean the typical uncontrolled, unreplicated, statistically insignificant sort of "let's add it, see what happens, and produce results that show how my tank never looked better" sort of trials that are often found in aquarium literature). The results showed a precipitous decline in nitrogen and phosphorus levels over approximately one month with increasing doses of vodka. The sample size for the experimental procedure was one (n=1), consisting of a single person's personal home aquarium. There were no controls in the experiment (i.e. an identical tank without vodka being added to see if there actually were results from the treatment). In fact, the sample tank received an increasing dose of vodka during the treatment, making any dosing effect impossible to determine. Additional support for the "experiment" was collected by casual replication in completely different trials in even less controlled conditions; that is, other aquarists began adding vodka and claimed similar "results."

Results of this work also showed a number of other effects. A large "bloom" occurred which clouded the test tank, an occurrence that could and often does kill tank inhabitants. It was assumed the bloom was bacterial, but no mention was made if and how the cloudiness in the tanks was determined to be bacterial. Given what I will offer below, it may also have simply been carbonate precipitation brought about by additional carbon addition and possibly microbial mediation. Having fortuitously escaped tank mortalities, the tank cleared and the authors literally state how "the tank water had never been clearer, the coral polyp extension was better, and the coral coloration was more intense." Where have I heard this before? The observed decrease in nitrate and phosphate is an interesting effect, but I will discuss this in more detail below.

Critique of the Method and Discussion

Without yet addressing the biological premise behind this concept, I feel the need to address other parts of the article. There are a number of statements and assumptions made by the authors which are unsubstantiated, not factual, or questionable.

The authors state that increased levels of nitrate cause decreased coral growth rates in their rationalization for ethanol-based reductions, but there are conflicting studies on this subject. There have been many studies that have shown declines in coral growth with increased levels of nitrogen (as ammonia or nitrate), as well as those which have shown increased coral growth with increased levels of nitrogen (as ammonia or nitrate), or no significant effects at all. The extensive works that exist on the subject discuss the effects of increased nitrogen on tissue growth, linear extension, calcification rates, reproduction, settlement rates, and other aspects of coral biology. Generally, increases in ambient levels of phosphate have been implicated in reduced coral growth, although recent works also conflict in this regard. ENCORE studies (Steven and Broadbent 1997), for example, showed a 29% increase in skeletal biomass with phosphorus enrichment in Acropora palifera. As stated in the article, "several recent field studies have found no change in growth rates in response to putative elevated nutrient concentrations, and challenge the dogma that corals can only grow in oligotrophic conditions as an oversimplification of processes that govern the growth of these organisms." Most recently, the discovery of corals harboring symbiotic extracellular bacteria (Rohwer, et al. 2001, 2002) and intracellular cyanobacteria (Lesser, et al. 2004) to provide a source of reduced nitrogen emphasizes the normally nitrogen-limited growth of corals in very low nitrogen environments such as coral reefs.

The authors write that denitrification occurs only in anoxic environments, and further state that such areas only occur deep within live rock or within sand beds. Their opinion is that tanks lacking sand beds may not have enough denitrification capability within the pore structure of live rock to process the metabolic or aquarist-provided nitrogen inputs to reef tanks. First, no denitrification rates, to my knowledge, have been measured in aquarium sediments or substrates outside those provided by Toonen (although they have been measured often in the field, as discussed below). Thus, the statement is speculative, at best. Second, most aquarists using live sand beds believe that top aerobic (oxic) layers overlay the anoxic layers where denitrification takes place. However, denitrification can also take place in oxic areas, and some of the highest rates of denitrification have been found in the top 1 cm of sediments where nitrate and oxygen levels are highest (Oren and Blackburn 1979). Denitrifying zones can occur from the top millimeter down to 10-15 cm or more, such as in the sediment areas near the Bermuda shelf. Nonetheless, anoxia commonly develops in the top 1/2" to 1" (5mm - 10 mm) of reef sediments, though this depth varies according to the grain size, bioturbation levels, water flow, physical sediment shifting, dynamic pockets of transient organic enrichment, and composition of the substrate. Areas without bioturbation may become anoxic within millimeters of the (carbonate) mud surface of shallow water sediments (Matson, 1985).

Moreover, denitrification has been shown to be a nitrogen-limited and not a carbon-limited process, though carbon limitation is central to the premise of the vodka-addition treatment. Without question, the denitrification process is microbially mediated, but unfortunately little, if any, evidence exists that microbial populations in aquariums are carbon-limited. In fact, in the presence of adequate light and a tank full of corals, along with buffer additions, kalkwasser additions, and normal gas exchange, carbon should be available in excess. There are studies that support the carbon-limitation of heterotrophic bacteria in marine bacterioplankton (Kirchman, et al. 2000), but these same studies along with others, also indicate iron, phosphate, or nitrate limitation in the same waters under different conditions. What conditions exist in a particular aquarium, what bacteria can be expected to "bloom," and how the system responds is far from assured. Also, denitrification probably does not appreciably occur in most anoxic environments, but is closely coupled with nitrification and occurs predominantly at the oxic/anoxic interface. In anoxic sediments, sulfate reduction seems to be the primary pathway, although even sulfate reducing bacteria are found in oxic environments (Dilling and Cypionka 1990; Ramsing, et al. 1993; Teske, et al. 1998; Minz, et al. 1999b; Minz, et al. 1999a; Fournier, et al. 2002; Schramm, et al. 1999; Sigalevich, et al. 2000). Sulfate reducers occur primarily in enriched lagoon sediments, and they are also associated with cyanobacterial mats in the reef flats (Kinsey 1985). The end product of their decomposition is carbon dioxide, which can contribute greatly to the CO2 content of the water.

Because of hydrodynamics across surfaces, microbial community dynamics, and other biotic and abiotic influences, oxic/anoxic zones can be found virtually everywhere in an aquarium. Denitrification has been found to exist on the surface of detrital particles, on the surface of corals, and on the surface of sand grains that are found in oxic environments. Therefore, denitrification and even sulfate reduction can be considered microaerophilic processes that do not depend on anoxia to take place. A microbiota adapted to the anoxic zone below the RPD (Redox Potential Discontinuity) environment can decompose organic material through fermentation, where some organics are used as hydrogen acceptors for the oxidation of other compounds, yielding end products such as fatty acids and dissolved sulfates. Nitrates, carbonates, and water can be used as hydrogen acceptors by different bacteria, yielding compounds such as H2S, NH3, CH4, etc. These are not ordinarily thought or propounded to be compounds desirable in captive conditions, yet the typical flora and fauna in a live rock-based system thrives on these exact compounds.

Furthermore, plants are able to utilize denitrification pathways, and aquariums contain high numbers of these; macroalgae and photosynthetic single-celled organisms, endolithic fungi, bacteria, coralline algae, and highly grazed turf species are among those functional biotic components present but remaining largely unseen or not considered in such speculations on nitrogen dynamics in tanks, and none of which are requisite to the presence of a sand bed. Sponges have been found to be able to denitrify, too, through their association with endosymbiotic bacteria. Corals are covered with a rich microbial surface community that includes many alpha- and gamma-proteobacteria that are known to be denitrifiers. In fact, anoxia is now known to exist within coral tissues at night, and studies are underway to determine how corals are able to survive this environment (Kulhanek, et al. 2004). Ultimately, the individual rates of denitrification within aquaria are probably largely dependent on an incalculable number of factors. If, and why, denitrification or phosphate accumulation is occurring in individual tanks is probably equally varied, and judging by the number of relatively novice reefkeepers in this country reporting immeasurable nitrate and phosphate levels, the problem may not be so widespread or insurmountable as is inferred by the authors.

Upon finishing the results section of this article, and progressing to the discussion, barely a sentence existed which could be taken as correct. I would urge those so inclined to read this article to completely skip the discussion section. Virtually every statement concerning disease nutrient processes, and microbial ecology is conjecture and, in many cases, simply wrong. This is unfortunate, because if the authors had a better grasp of the processes occurring, had done adequate work to confirm their speculations, and focused diligently on a good experimental protocol, the effects noted in terms of such mismanaged aquaria that have high nitrogen and phosphorus levels (that admittedly are common enough) and their response to carbon inputs might lead to valuable developments (though I doubt a dosing schedule for vodka across all reef aquariums with such issues would be possible).

"Of course, if one ignores contradictory observations, one can claim to have an 'elegant' or 'robust' theory. But it isn't science." - Halton Arp, 1991, from Science News, Jul 27.

Some Studies on the Subject

"There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact." - Mark Twain (1835 - 1910).

The amounts of bacterial populations present in sediments depend to a large degree on particle size (Rublee 1982, Ransom, et al. 1999). They are the highest in very fine sand year round and in very coarse sand during the winter (Johnstone 1990, Matson 1985). Sediments are generally oxidized in winter, and reduced in summer since higher temperatures favor higher anaerobic activity. Coarse sand has higher photosynthesis rates of algae within the sediments, and in overall respiration of the community (Johnstone 1990). Even coarse-grained sediments have a rate of anoxic catabolism that equals oxygen reduction (Matson 1985). Bacterial populations in sediments, as mentioned above, may even be nutrient limited (Hansen 1987) by phosphorous or nitrate; in other words, they are so effective that they could theoretically process more organic material than the amounts to which they are exposed. Anoxic decomposition, via reduction, is the most completely regenerative method of disposing of excess nutrients, and could account for the decomposition of all deposited organic matter to the lagoon (Matson 1985). The same findings have been applied to seagrass meadows and mangroves, and I have never seen any sand bed in an aquarium anywhere nearly as foul and organically enriched as some of these habitats that reek of hydrogen sulfide (and yet still harbor a tremendous variety of filter feeding invertebrates, sponges, and even corals).

The sediments that surround and lie adjacent to coral reefs can be quite high in organic matter, especially in small pockets, and play an integral role in denitrification and nutrient processing. The highest rates of denitrification on and around the reef are found in dead coral heads (this is the equivalent of live rock to aquarists), Thalassia seagrass beds and lagoon sediments (Seitzinger and D'Elia 1984). The fact that dead coral heads show such high rates of denitrification seems to contradict the notion that live rock is an ineffective substrate as posed in the above-mentioned article. It is conceivable, however, and perhaps likely that the biomass per volume of water in tanks exceeds the abilities of live rock to process organic and inorganic nutrients, but this additional amount is met easily by utilization of a sand bed by aquarists as evidenced by extremely low nutrient levels found in the water column over long periods of time. I am quite sure no work has been done to obtain meaningful measurements of organic enrichment as an average value in reef aquariums, but observation would suggest that they are significantly enriched by comparison with an equivalent sand depth around coral reefs, and perhaps about equivalent to offshore Thalassia meadows (but less enriched than nearshore communities). If this estimate is even remotely reasonable then, if anything, the sand beds of tanks should be operating maximally in terms of microbial function. The work of Toonen (see above) would tend to support this statement, as well.

The mineralization of organic matter, although dependent on anaerobic processes, can be significant. Organic detritus (mostly algal debris and coral mucus) is decomposed primarily by microbial action. In an experiment using Zostera detritus and living plants, over half the oxidation and reduction of organic matter could be attributed to the sulfate and nitrate reducing bacteria (Jorgenson and Fenchel 1974). Up to 80% of dissolved organic compounds (DOC) pass through and are absorbed by the lagoon community, and most of the particulate organic compounds (POC) settle on the lagoon sediments (Ogden 1988). Sandy lagoons also account for more than 70% of the nitrogen fixation in the reef (Shasar 1994). A slow downward flux of O2 appears to be at least partly responsible for sedimentary anoxia (Matson 1985). The end products of anoxic decomposition are returned to near the sediment surface, where they feed a diverse microflora involved, once again, in primary productivity.

What are the fates of nitrate? There are many, but among the most prominent are assimilation by algae and bacteria, and dissimilation by bacteria (reviewed in Herbert 1999; also see the online review by Lomstein and its associated references). The upper oxic layers of bacteria oxidize organics to CO2 that can be used by algae or corals for calcification and/or respiration (Skyring 1985). The anaerobic fermenters and denitrifiers oxidize organics to CO2 and convert nitrate to ammonia and dinitrogen gas N2. Terrestrial and estuarine muds have higher rates of dissimilatory nitrate reduction back to ammonia (and not nitrogen gas), thereby conserving nitrogen in the system for use by photosynthesizing organisms within the sediments (Kim, et al. 1997 and also see associated references). This is also gaining acceptance as the primary mode of action in marine sediments, as well. In the reduction of nitrate to nitrogen gas, nitrogen is simply removed from the system by release into the environment. There is a low pH in most anoxic sediments, and therefore carbon dioxide (CO2), and organic acids produced by the N2 community may then be shunted to sulfide reduction and methanogenesis only if anoxic conditions exist. The degree to which anoxia exists in tanks is not known, and even deep sand beds may have limited conditions of anoxia within the porewater spaces. These sulfide and methanogenesis groups, living with redox levels as low as -450 mV, probably exist in aquaria. In general, redox levels lower than -200mV indicate that the beneficial reduction processes are taking place.

Bottom sediments and their accompanying flora and fauna are among the most important ways of recycling organic reef material (Sorokin 1981). The coral reef and its adjacent communities are very effective in absorbing nutrients and recycling them within the community, preventing loss of such energy sources back to the ocean, and therefore allowing the vast complex web of species to exist (Crossland and Barnes 1983). They are largely dependent upon each other. Kinsey (1985) states that, "gross production and calcification in coral reefs are, nevertheless, clearly dominated by benthic processes." From the preceding information, it should be obvious that an effective sediment in terms of decomposing and denitrifying ability is one that is high in organic material that supports copious microbial populations. However, such rich benthos also support communities of meiofauna, macrofauna and flora. Primary deposit feeding macroinfauna of lagoonal systems include the sea cucumbers, gastropods (Tellina sp., Rhinoclavis sp., Strombus sp., etc.), bivalves, echinoderms, and certain fish such as the tommyfish (Limnichthys sp.) and gobies (Amblyeleotris sp.)(Ogden 1988).

One particular animal that has been found repeatedly to dramatically influence the productivity of lagoonal sediments is the thallasinid shrimp (Callianassa sp.). These shrimp, which burrow into the sand and create small mounds of substrate around their burrows, are both prolific and efficient. Thallasinids are very effective "substrate sifters," and they significantly reduce the micro- and meiofaunal populations. "(Callianassa) play a major role in the restructuring and functioning of lower trophic groups in lagoonal sediments." (Hansen, et. al. 1987, Johnstone 1990). The meiofaunal consumers such as protozoans, ciliates, nematodes, copepods, turbellarians, polychaetes, and annelids also scavenge the sediments for detritus, algal remains, and may even forage on bacteria directly. Many macroalgae may be present that vie for the rich organic content of lagoonal sediments. The most competitive are members of the genera Microdictyon and Caulerpa. Caulerpa may significantly uptake ammonia produced from microbial action via their rhizoids (Williams 1985). Microbial sedimentary populations include viruses, bacteria, fungi, actinomycetes, molds, yeasts, and unicellular algae.

In general, bioturbation and competition negatively affect microbial populations. Therefore, the overall effectiveness of sediments in nutrient regeneration is somewhat reduced in the presence of other biota over what would be present through the actions of microbes alone. It is interesting that many proponents of "live sand beds" still recommend the use of "substrate sifting" organisms such as sea cucumbers, sleeper gobies (Valencienna sp.) and other burrowing animals. Such bioturbation does mix the upper layers of the sand and, in effect, cleans it of organic material. However, they also remove substrate for microbes, change the oxygen composition of the sand, and alter resident bacterial populations. Keeping the sand "clean" should not be considered a priority given the immense capabilities of the microbes and associated organisms.

"The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' (I found it!) but 'That's funny...' " - Isaac Asimov (1920 - 1992).

Putting It All Together

"Technology is the knack of so arranging the world that we do not experience it." - Frisch, Max (1911-) b. Switzerland.

I was recently talking with a well-known aquarist who was trying to convince me of the need to use phosphate removing compounds and apparatus to have a really successful reef aquarium. His points were well taken - low phosphate levels do seem to be an important aspect of a successful tank. But, I explained, I did not have a phosphate problem, and haven't for many, many years. He suggested that it must be because I don't feed much, or that I had few fish, or that I did a lot of water changes. No, No, and No. Perhaps I didn't stock the levels of fish that some people do? True. I feel that if fish cannot exist in captivity in a reasonable facsimile of their environment that allows them to display relatively normal behaviors, I don't like keeping them (although I admit that I do have quite a number of fish for various reasons that fit into the unnatural category. But, even the ones I purchased and chose on my own to keep are old and from my earlier more exuberant days and they will stay with me until the end of their lifespan). I also don't find tanks crammed wall-to-wall with fish very attractive or desirable. But, I think twenty fish in my tank is plenty, and far over what would be found in an equivalent space on the reef. Questions arose about my nutrient export devices. Apparently, my skimmer was somewhat inadequate, too. How could I have such low nutrients?

Well, for years, and despite good coral growth, I didn't have such low nutrients, and I regularly found my nitrates in the 5-10ppm range, and phosphates around 0.1ppm as measured at the time by hobby test kits. This was during the time when I ran a "Berlin system." My nutrients dropped to immeasurable levels when I added a sand bed, and they have remained that way ever since.

I would offer a few suggestions to those troubled by certain issues:

1. If the tank has low measurable nutrient levels, and low particulates in the water column, add food.

2. Bacterioplankton in tanks as a trophic source may not be the ideal area to address. Plenty of bacteria become waterborne each time the glass is cleaned, each time a crustacean or fish or snail moves through the sand, each time a fish poops or swims through the water releasing mucus from their skin, as corals release mucus, as organisms bore into substrate, and they probably bloom briefly and transiently with food additions. In addition, corals have huge microbial populations on their surfaces and in their gastric cavity, and a ciliated epidermis. Need I say more?

3. Sand beds are not nutrient traps unless seriously mismanaged, in which case the problem is with the aquarist and not the sand. If mismanaged and a chronic problem, simply yell "do-over" and fix the problem and not repeat the problematic behaviors that initiated it in the first place. The sediment communities and associated microbial communities are the major source of nutrient processing, decomposition, recycling, and remineralization in the wild, and likely in tanks, as well.

4. If a tank has high nutrients in the water column, a hose, bucket of water, and bag of salt cures it. It is cheap and works every time. There will be no heated debate as to the efficacy or downsides of its effectiveness. There is no regular maintenance required, no replacement of media, and no "experimentation" required. When coupled with two containers, a small powerhead, some more hose, and a timer, automated water change apparatus can be accomplished for about $20-50, depending on the size of the containers. Future water changes will cost exactly as much as the salt and water required to fill the input container. No worries about diseases, blooms, oxygen drops, media replacement, leaching, or anything else. For the fifteen years since I started keeping reef aquaria, the reluctance of most aquarists to do water changes, but willingness to invest extraordinary and often frustrating amounts of time, money and effort into products, techniques, and equipment to avoid a simple procedure has baffled me. If you don't have the time or inclination to make up seawater and do a water change, you probably don't need to be keeping marine animals as a hobby.

5. Nutrients in aquaria are not just a matter of input and export. Uptake is significant. Calcium levels, normally at 400-450ppm, are taken up by my tank at a rate that I must replace the calcium every two days, and I try to do it daily. The same is true of alkalinity. Almost every organism kept in aquariums, and assuredly the lion's share in terms of biomass, can either directly take up dissolved and particulate material, or be involved directly or indirectly in decomposition pathways. The uptake of nitrogen and phosphorus directly and incorporation into biomass by growth and reproduction should not even raise an eyebrow in terms of the orders of magnitude less of these substances that exist. If my coralline algae, snails, corals and mollusks can produce enough skeletal material to remove 30ppm of calcium per day from my tank, I would hope they and every other non-calcifying organism in my tank is growing or reproducing enough to take up immeasurable levels of nitrogen and phosphorus and put it into tissue growth. If they aren't, I'm doing a bad job at growing things.

Plants require fertilizer regularly because they grow. Terrestrial animals require food to grow. Why, exactly, do we think that the same doesn't hold true for aquariums packed with life? If I feed a certain amount of food to my tank, and obviously there is no food in the water moments or even hours later, the only thing left is secondary production; wastes and excreted material are all that's left to feed the huge array of creatures in the tank that did not happen to capture anything directly, and that ain't much. But it works, just like it does on the reef. The recycling of nutrients given the diversity in reef aquaria is exactly the same as on coral reefs in terms of the processes involved. True, we lack the dilution effect of the ocean water, but coral reefs don't have skimmers, either. Furthermore, the increased "bioload" of consumers is also matched by an increased "bioload" of producers (corals, algae, etc.). While unmeasured, it would be a virtually impossible biological situation to not see a similarly increased "bioload" of microbial communities, as well. I am, therefore, as concerned as ever that despite everything, one of the primary limitations of my tank (and most tanks) is how to provide enough food. If we can accomplish this, perhaps the survival of azooxanthellate species we long to keep will be made possible. These are the questions to ask and the problems to surmount.

Can we add more food if we reduce nitrates by adding vodka? Why vodka? Why not sugar? And if sugar, why not more photosynthetic organisms to produce the sugar? And why not more corals to produce polysaccharide rich mucus? Would adding more corals reduce nitrate? Actually, they would and they do. A long time ago, when Steve Tyree had promoted the use of sponges for natural filtration, I suggested corals would accomplish the same purpose. Coral filtration…now that's really up my alley!

"All truly wise thoughts have been thoughts already thousands of times; but to make them truly ours, we must think them over again honestly, till they take root in our personal experience." - Johann Wolfgang von Goethe (1749 - 1832).

Conclusion

"We may define "faith" as a firm belief in something for which there is not evidence ... Where there is evidence, no one speaks of "faith". We only speak of faith when we wish to substitute emotion for evidence." - Bertrand Russell, 1955.

It may be surprising to learn that a great portion of the information written above came from an article written in 1998 by some guys named Eric Borneman and Jonathan Lowrie, and appeared in the June issue of Freshwater and Marine Aquarium magazine. If one looks at the references, much of the information on carbon, nitrogen and phosphorus dynamics was well known in the 1970s and 1980s, with many direct studies on coral reefs. Now, I may not know much, but I do know that in the twenty or so years that we have been keeping corals alive, it has become obvious that the apparatus that was so heavily depended upon in the early years to simply maintain corals, such as denitrators, bioballs, phosphate removal media, and others, is no longer required. John Tullock (1997) stated eloquently that we needed "more biology and less technology." Those words have come true to a great extent, and concurrent with better technology. The result is that we now have reef tanks easily capable of being maintained with immeasurable levels of phosphate and nitrates, our corals show outstanding growth and coloration to the point where many of us are searching for places to rid ourselves of excess growth of some species, and corals literally grow out of the tank. Such aquaria are regularly featured as the tank-of-the-month in this magazine. Removing functional natural processes and replacing them with experimental methods and apparatus seems to me like a bad idea. It didn't work very well in the 80s, and I don't think it will work well today, either.

I consider "long-term" in aquariums to be on the order of years. The debates being mentioned above have occurred within the past year, and already fierce proponents extol the relative benefits and detriments of one way or the other. My view is that time and adequate experimentation and measurement will tell the tale. To me, having a 6" deep sand bed for eight years with no measurable nitrate or phosphate and no regular or intentional water changes says something. I have outstanding coral growth and great coloration. In fact, my tank has never looked better. I'm keeping the vodka for myself.

"I dreamed a thousand new paths . . . I woke and walked my old one." - Chinese proverb.

References

Adey WH. 1983. The microcosm: a new tool for reef research. Coral Reefs 1: 193-201

Alongi DM. 1988. Detritus in coral reef ecosystems: fluxes and fates. Proc 6^th Int Coral Reef Symp, Townsville 1: 29-36.

Crossland CJ, and DJ Barnes. 1983. Dissolved nutrients and organic particulates in water flowing over coral reefs at Lizard Island. Aust J Mar Freshw Res 34: 835-44.

D'Elia CF, and K. Webb. 1977. The dissolved nitrogen flux of reef corals. Proc 3^rd Int. Coral Reef Symp, Miami 1: 325-30.

Dilling W, and H Cypionka. 1990. Aerobic respiration in sulfate-reducing bacteria. FEMS Microbiol Lett 71:123-128.

Fournier M, Z Dermoun, M-C Durand, and A. Dolla. 2002. A new function of the Desulfovibrio vulgaris Hildenborough [Fe] hydrogenase in the protection against oxidative stress J Biol Chem 279: 1787-1793.

Herbert RA. 1999. Nitrogen cycling in coastal marine ecosystems. FEMS Microbiol Rev 23: 563-590.

Jaubert J., 1989. An integrated nitrifying-denitrifying biological system capable of purifying seawater in a closed circuit aquarium. Bull. Inst. Océanogr. Monaco 5: 101-106

Jørgensen BB, and T Frenchel. 1974. The sulfur cycle of a marine sediment model system. Mar Biol 24: 189-204.

Kim D-H, O Matsuda and T Yamamoto. 1997. Nitrification, denitrificaton and nitrate reduction rates in the sediment of Hiroshima Bay, Japan. J Oceanogr 53: 317-324.

Kinsey DW. 1985. Metabolism, calcification and carbon production: systems level studies, Pt. I. Proc. 5^th Int. Coral Reef Symp, Tahiti 4: 505-26.

Kirchman DL, M Benedikt, MT Cottrell, DA Hutchins, D Weeks and KW Bruland. 2000. Carbon versus iron limitation of bacterial growth in the California upwelling regime. Limnol Oceanogr 45:1681-1688.

Kulhanek E, D Zoccola, C Sabourault, E Tambutte, S Tambutte, D Allemand. 2004. Cnidarians: a biological model for the study of gene transcription during hypoxia. Proc 10^th Int Coral Reef Symp, Okinawa Abs: 323.

Lesser MP, CH Mazel, MY Gorbunov, and PG Falkowski. 2004. Discovery of symbiotic nitrogen-fixing cyanobacteria in corals. Science 305: 997-1000.

Matson EA. 1985. Anoxic catabolism in the shallow carbonate muds of Bermuda. Proc 5^th Int. Coral Reef Symp, Tahiti 3: 422-7.

Minz D, JL Flax, SJ Green, G Muyzer, Y Cohen, M Wagner, BE Rittmann, and DA Stahl. 1999. Diversity of sulfate-reducing bacteria in oxic and anoxic regions of a microbial mat characterized by comparative analysis of dissimilatory sulfite reductase genes. Appl Environ Microbiol 65: 4666-4671.

Minz D, S Fishbain, SJ Green, G Muyzer, Y Cohen, BE Rittmann, and D. A Stahl. 1999a. Unexpected population distribution in a microbial mat community: sulfate-reducing bacteria localized to the highly oxic chemocline in contrast to a eukaryotic preference for anoxia. Appl Environ Microbiol 65: 4659-4665.

Mrutzek M, and J Kokott. 2004. Ethanoldosierung im Aquarium - neue Wege zur Verbesserung der Lebensbedingungen. Der Meerwasseraquarianer 8: 60-71.

Ogden JC. 1988. The influence of adjacent systems on the structure and function of coral reefs. Proc. 6^th Int. Coral Reef Symp, Townsville 1: 123-9.

Oren A, and T H Blackburn. 1979. Estimation of sediment denitrification rates at in situ nitrate concentrations. Appl Env Microbiol 37: 174-6.

Ramsing N B, M Kühl, and BB Jørgensen. 1993. Distribution of sulfate-reducing bacteria, O2, and H2S in photosynthetic biofilms determined by oligonucleotide probes and microelectrodes. Appl Environ Microbiol 59:3840-3849.

Ransom B, RH Bennett, R Baerwald, MH. Hulbert, and P-J Burkett. 1999. In situ conditions and interactions between microbes and minerals in fine-grained marine sediments: A TEM microfabric perspective. Am Mineralog 84: 183-192.

Rohwer F, M Breitbart, J Java, N Knowlton, and F Azam. 2001. Microbial diversity of scleractinian corals. Coral Reefs 20: 85-95.

Rohwer F, V Seguritan, F Azam, and N Knowlton. 2002. Scleractinian corals as microbial landscapes. Mar Ecol Progr Ser 243: 1-10.

Rublee PA. 1982. Seasonal distribution of bacteria in salt marsh sediments in North Carolina. Estuar Coast Shelf Sci 15:67-74

Schramm A, CM Santegoeds, HK Nielsen, H Ploug, M Wagner, M Pribyl, J Wanner, R Amann, and D de Beer. 1999. On the occurrence of anoxic microniches, denitrification, and sulfate reduction in aerated activated sludge. Appl Environ Microbiol 65: 4189-4196.

Scoffin,VP, and AW Tudhope. 1985. Sedimentary environments of the central region of the Great Barrier Reef. Coral Reefs 4: 81-93.

Seitzinger SP, and CF D'Elia. 1983. Preliminary studies of denitrification on a coral reef. The Ecology of Deep and Shallow Coral Reefs. NOAA Symp. Series for Undersea Res 1: 199-208.

Shasar N, Y Cohen, Y Loya, and N Sar. 1994. Nitrogen fixation (acetylene reduction) in stony corals: evidence for coral-bacterial interactions. Mar Ecol Prog Ser 111: 259-264.

Sigalevich P, E Meshorer, Y Helman, and Y. Cohen. 2000.Transition from anaerobic to aerobic growth conditions for the sulfate-reducing bacterium Desulfovibrio oxyclinae results in flocculation. Appl Environ Microbiol 66: 5005-5012.

Skyring GW. 1985. Anaerobic microbial processes in coral reef sediments. Proc 5^th Int Coral Reef Symp, Tahiti 3: 421-5.

Sorokin YI. 1981. Microheterotrophic organisms in marine ecosystems. In: Analysis of Marine Ecosytems (A.R. Longhurst, ed.). pp. 293-332.

Steven ADL, and AD Broadbent. 1997. Growth and metabolic responses of Acropora palifera to long-term nutrient enrichment. Proc 8^th Int Coral Reef Symp 1: 867-872.

Teske A, NB Ramsing, K Habicht, M Fukui, J Küver, BB Jørgensen, and Y Cohen. 1998. Sulfate-reducing bacteria and their activities in cyanobacterial mats of Solar Lake (Sinai, Egypt) Appl Environ Microbiol 64: 2943-2951.

Wiebe WJ 1985. Nitrogen dynamics on coral reefs. Proc. 5^th Int. Coral Reef Symp, Tahiti 3: 401-6.

Williams SL, IP Gill, and SM Yarish. 1985. Nitrogen cycling in backreef sediments. Proc 5^th Int. Coral Reef Symp, Tahiti. 3: 389-94.