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/The Conscientious Marine Aquarist

Reef Systems, An Introduction

What is A Reef Aquarium? Lighting? Filtration?

By Bob Fenner

To "fuge" or not to "fuge"...

Small Marine Aquariums
Book 1: Invertebrates, Algae
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by Robert (Bob) Fenner
Small Marine Aquariums
ook 2: Fishes
New Print and eBook on Amazon: by Robert (Bob) Fenner
Small Marine Aquariums Book 3: Systems
New Print and eBook on Amazon:
by Robert (Bob) Fenner

What is a reef aquarium? A reef set-up can be defined in at least three ways; 1) by the organisms it employs and sustains, 2) it's refined equipment (in particular filtration and lighting), and lastly, 3) as a function of the high, consistent water quality the first demands and the second produces.

Reef life is the a priori cause of why aquarists strove so long to ascertain just what it would/does/will take to keep such systems. The beautiful corals and several related stinging-celled animal groups, live algae, sponges, crustaceans, mollusks, the m?ange that makes up "live-rock" and "live-sand" and oh-so-many more used to virtually impossible to keep. My personal odyssey in the hobby, science and business of captive aquatic life spans the recent decades of these endeavors; the 1960's forward. I can remember whole tanks, indeed shipments of marine invertebrates "melting down" due to mysterious "water quality", filtration, lighting, who-knew-what reasons.

Modern reef systems go beyond simply keeping the more delicate fish and non-fish life found on the world's reefs alive; they actually grow and reproduce them; often at higher than natural rates!

Improvements in marine-aquarium keeping equipment get equal credit with livestock collecting and shipping techniques, and hobbyist knowledge as determinants driving reef interest. Especially, light fixtures and lamps/bulbs, and filter gear have allowed the successful maintenance of reef-life. More than new technologies developed for the ornamental fish industry per se, much of our innovations have come from borrowing from other fields. Magnetic-driven fluid-moving pumps with non-corrosive volutes, impellers, seals and shafts came to aquariums by way of the chemical-handling fields. True full-spectrum fluorescent lamps like Vita-lites ™, were introduced back in the sixties for indoor gardening and industrial uses. Similarly, wet-dry or trickle-filter applications are borrowed from turn-of-the-century municipal sewage-treatment principles. Regardless of where they come from, good ideas are good ideas; and these and many more have come to us from totally unrelated fields.

A true oxymoron of reefs, wild and kept is their chemical and physical polar nature; they're both dynamic and homeostatic. Reef aquarists must employ all the tricks available to them; careful d?or selection, sparse , appropriate livestock with careful feeding, diligent maintenance… to provide optimized, consistent water quality.

Due to their geographical positions and biota reef systems are typified as being "stable", "self-adjusting" and "nutrient-poor". The stereotypical reef habitat (there are several classifications of their diverse ecoclines) does receive a pretty regular amount of solar insolation, displays a narrow range of thermal variation, chemical make-up, and other physical factors. Such regularity is more than desirable in a captive reef environment; it is requisite. Temperature, salinity, pH, ammonia/nitrite/nitrates used to be the only water-quality testing concerns of marine aquarists. With reefs we've added reduction-oxidation, electrical current, ultraviolet radiation, phosphates, silicon, calcium, and more.

What is "Reef" Filtration? Rather than any given technique, filtering for reef system's involves various strategies that result in homogeneous, clean, well-oxygenated water. Almost always, reef filtration includes vigorous, non-linear (i.e. chaotic) circulation, generated by one or more fluid-moving pumps and/or powerheads. Typical turnovers are several times per hour; there is no practical limit. Actual filter modes, media and containers are highly variable. Separate sumps/refugia, some fitted with wet-dry/trickle media, rock or sand, protein-skimmer/foam fractionation, re-dox/ozone/ultraviolet systems, calcium reactors, chemical contactors… There are many individual and confluent schools of how to go; Jaubert/NNR (Natural Nitrate Reduction), Berlin methods, electrical and chemical filtration modes… Canister, pressurized, high-tech, low-tech, no-tech… All with their own adherents and acolytes. Are any better than the others? You bet; depending on YOUR application, YOUR pocketbook, and YOUR penchant for tinkering and adjusting. Take a look through your livestock fish store (LFS; yes, another acronym), and the hobby literature. What's hot and available changes each issue. As a conscientious reef consumer, you are compelled to study up and keep current. Just "keep your eye on the prize"; remember, what you are seeking is the most consistent, high-quality water at the lowest hassle and cost.

A few constants (in general). Though I worked for Earl Kennedy in the Philippines in the sixties,

and have seen numerous examples of "live-rock only" systems in Indonesia and elsewhere in the intervening years, most reef-keepers will employ a protein skimmer, aka foam fractionator as their reef filtration principal component. Choose well. Just because it says "venturi" on the label, does not make a given brand, make or model better than one that is not. And, no, price is no good indication of value or relative functionality. Talk with your dealers and other practicing "reefers" (even if you're "out in the boonies", they're accessible via the internet); they are your best source of current, accurate, significant and meaningful information.

Better "live rock" and sand is worth the cost. Which is which? Study and decide for yourself. Are all those meters, dosers and pumps necessary? No, but reliable testing and delivery gear can be of great service to those who will employ it properly. Just as with any tool, neglect or inappropriate use is worse than having none at all. There are only good pumps and powerheads, and "the rest"; you want only the former. One's that are adequately powerful pressure/volume wise, chemically inert, serviceable and reliable.

What about light and lighting in the reef aquarium? Light is very important to reef life. Even for non-photosynthetic organisms the regularity of illumination is of consequence; much of their behavior and endogenous rhythms are tied to light cycling.

There are three aspects of light that concern reef hobbyists; quality, quantity and duration. Photoquality is a question of the "kinds" of light; wavelengths principally. Some radiation bandwidths are toxic, such as far-end ultraviolet. For algae and livestock that harbors endosymbiotic algae, such as many of the true corals, sufficient light of certain wavelengths is necessary to drive the light reaction of photosynthesis.

Photo-quantity is a matter of the intensity or brightness (apparent or not) of light. The number of photons is as important as their wavelength; not enough light, insufficient photosynthesis and way too little, everybody bumping into each other.

Photo-duration is the periodicity of light cycling. Regular on-off light/dark periods are important, and easily achieved with simple to complex timing mechanisms. Gradually turning on and off some lighting is preferable to all on/off, and some sophisticated schemes can mimic diurnal sunniness, moonshine, even every now and then cloudiness!

Happily, there are a few different methods of providing proper light to captive reefs. Most notably, metal halides (MH) and various formats of full-spectrum fluorescents (regular, high, and very-high outputs, compacts). These devices and some more novel types are utilized to provide reef set-ups with adequate quality and quantity light spectra.

 David; what do you think? Too simplistic? Is this about the level of information and reading level you have in mind? Am going to crank out my first feature for you in a few… how 'bout: Get thee to a Refugium? Okay!

Reef Systems: An Overall Picture:

At the pinnacle of demands for optimum and consistent water quality are so-called reef systems. These units can be distinguished on the basis of their gear; specialized lighting and filtration and/or the full-spectrum of life they ideally support.

There are few human-made works of art (I can't think of any) that compare with a full-blown tropical reef set up, with incredible shapes, colors, patterns in algae, fishes and invertebrates, all mixing and moving in their ways.

There are no "secrets" to producing and keeping such a collection; only a few steadfast rules regarding lighting, filtration-results, and set-up. We'll cover these in turn.

Reef aquariums are not for everyone; they are expensive to build-out, furnish, populate and maintain, time-consuming, and of types of marine systems, those most prone to "disaster". For these reasons and more, I implore you to practice on the less-demanding set-ups we've discussed so far, and to read some of the several excellent specialty books in this field before going further.


Largely depending on what kinds of photosynthetic organisms, and how hard you want to "drive" them, the intensity and quality of light is a function of arranging a mix of full-spectrum fluorescent lamps and fixtures, in whatever output formats. As a matter of looks, metal halides and other novel illumination may be considered for increasing system brightness and human appreciation.

Study of the variety and species of reef life available to you will reveal that some organisms are near-surface or deeper-water that require more/less light. They should be placed accordingly so that they neither "burn" or fade from lack of light.


Going out and measuring water quality parameters in the wild, what do we find? Not surprisingly very high and constant pH, conductivity, Redox, dissolved oxygen... and virtually no "metabolites" or chemical nutrients (ammonia, nitrite, nitrate, cresols, phenols, phosphate). Why? For one, because of currents that vigorously mix the air, beat calcareous materials into solution; that by themselves and 'feeding' photosynthetic organisms (mainly planktonic algae) raise the "desired" physical/chemical values. Currents otherwise "blow pollutants/nutrients away" into the "sink" which is the world's oceans.

Secondly, in synergy with the action of the oceans currents, the sum-total action of living processes on the reef absorb, web, net, accumulate and distribute what they can from the non-living world and each other.

What this means to the aquarist is that their artificial filtration must be vigorous and exacting in removal of excess materials/chemicals from the water. There are two approaches or ways of readily accomplishing these ends. Let me tell you of the one I was part of as a boy first.

My initial exposure to "reef-keeping" occurred in the mid-sixties as a worker bee for a Philippine wholesaler. I saw the large (for the time), a few hundred gallon concrete and glass tanks of Earl Kennedy in Manila, stocked with live rock, corals, some other invertebrates, with a few fishes. How was this miracle of keeping all these animals alive accomplished? Lollipop's (Earl's pet name) approach to reef-keeping was extensive (as opposed to modern system's intensive); we used "natural" lighting; he had very sparsely populated tanks with Spartan feeding.

We would go out and collect the planktonic food with window screens hung over the side of a panga (boat) sieving out what we could from the surface. Mr. Kennedy would feed very little of this daily.

Current "intensive" reef filter technologies include variations on the theme of wet-dry trickle filters, "Berlin" skimmer as-a-principal or only filter, algal-scrubbing adjunct, and other live rock/algae/sand formats. These systems are crowded with life, much more than earlier versions.


 Though there are many sub-types of reef systems, some with a focus on organisms not found at the water's surface, some "cold-water", none should be denied the benefits of energetic water flow. Some writers endorse the use of "extra" or alternate fluid moving mechanisms not associated with filtration; whatever you utilize, make it brisk. Reef organisms are simulated by strong flow, and water movement serves to diffuse and distribute oxygen and wastes. Though there are many sub-types of reef systems, some with a focus on organisms not found at the water's surface, some "cold-water", none should be denied the benefits of energetic water flow. Some writers endorse the use of "extra" or alternate fluid moving mechanisms not associated with filtration; whatever you utilize, make it brisk. Reef organisms are simulated by strong flow, and water movement serves to diffuse and distribute oxygen and wastes.

Live Rock/Sand:

An integral part of all reef systems is the use of calcareous rock and/or sand (see photo). This catch-all "live" and non-living material performs several critically important functions; in reality, it is what makes the system a reef.

Chemically and physically the living and non-living components of this 'decor' ameliorate water quality. Calcareous matter buffers the pH. The biological processes that all the types of life that are the "live" component of the material render the system's water more nutrient-free.

Biologically, "everything under the sun" comes attached and in between the rock and sand. I've seen octopuses, mantis shrimps, sponges, stinging-celled animals of every type, even fishes as "freebies" on/in live rock. These communities can add and take away so much from your intended livestock. They can be food as well as fodder for hobbyist complaints. Stinging fireworms, fire corals, mantis shrimps and other unwanted hitchhikers are as common as desirable forms in live rock. And "sand" is not much "better/worse".

A few useful points concerning live rock and sand. They should be calcareous, made up mainly of aragonite/calcium carbonate, not sedimentary or siliceous. I've seen non-"coral" based materials offered for sale in the trade. Don't buy them, they don't do the jobs the calcareous materials do.

Smell it, live rock/sand have an "ocean" odor, clean and distinct, not rotting. See my further notes below on Set-Up concerning live rock/sand.


You are referred to the previous three Sections on proper procedures for putting a marine system together. The components may be different in specifics, but their operation and order of introduction are the same.


The biggest difference here is really just a matter of degrees. A functional "reef" system very readily processes metabolites to non-noxious forms. Whatever design/engineering/operation model you use, wet-dry-under-tank, "Berlin", "algal-scrubbing", et al. technology the intent is to quickly and thoroughly remove toxic biological products and by-products. The biggest difference here is really just a matter of degrees. A functional "reef" system very readily processes metabolites to non-noxious forms. Whatever design/engineering/operation model you use, wet-dry-under-tank, "Berlin", "algal-scrubbing", et al. technology the intent is to quickly and thoroughly remove toxic biological products and by-products.

Protein skimming 

Is different here as well. As you'll recall, we waited with fish-only systems to turn our fractionator on after nutrient cycling was established. In fish and/or just invertebrate systems, this tool's use was initiated between the cycling and the introduction of non-fishes. With "reef" systems, the skimmer should be on full-tilt before the introduction of any livestock. Which conveniently brings us to:


What is the largest living "thing" on this planet? I'll give you a clue, it always has been the biggest life form. Still stumped? We'll many Life-Science types consider barrier reefs, with the GBR (Great Barrier Reef) of Australia, being the current winner, to be "one large super-organism". My point is, though western reductionistic notions define a separation between those who believe them and the rest of their environment, the real living world is inseparably, indistinguishably interlocked with it's "outside". Live rock and sand are (part) of the living reef in the wild and in captive systems.

Author's vary in their advice as to how and when to place live rock and/or sand into a "reef" tank. Some suggest putting it in a separate sump, placing part at a time, "curing" it in a quarantine facility... Here's my take on the issue; after setting up and checking the environmental gear and controllers for a week as previously prescribed, place all or ostensibly all the live rock/sand into the system. Do I suggest you rinse it in some of the "aged" seawater? Sure, if it's real stinky; otherwise just put it in. Live rock goes in over non-living "base" rock (coral skeletons), the sand as your purveyor instructs.

A rapid "succession" of events occurs, that can be a visual and olfactory shock to the uninitiated. Be patient.

Next comes a waiting period, a few weeks (generally 2-4) for those elements in the mix to die, eat, be eaten; make the system ready for the addition of (more) invertebrates and possibly algae and fishes.

With your test-kits you'll record a more or less standard scenario of nutrient cycling, but with a twist; if/when you detect the accumulation of nitrates, they will probably start to decrease at some point. Welcome to the world of real reef keeping.

Ongoing Maintenance:

A properly set-up and stocked reef system is actually the closest thing marine systems have to being maintenance-free. With attention to balancing the living and non-living components of a reef set-up, they become homeostatic. This being said, the average reef-keeper does spend a few to several hours a week checking water chemistry, adjusting salinity, feeding the livestock, and generally fooling with the system; it's just so enjoyable, most aquarists are unaware of, or don't begrudge the time commitment.


I don't want to dissuade you from pursuing a "reef-system"; my intent is only to urge your considering what an involved enterprise it is. Most tropical reef set-ups have thousands of dollars into them, with their keepers spending hundreds more a month on gear, organisms, food, electricity... and the animals living an average of a few months. Is this challenge for you?

Bibliography/Further Reading:

Belorusky, Wyn, Jr. 1988. How to build a living reef system. FAMA 5/88

Blackburn, Wayne. 1988. Corals in the reef tank. FAMA 12/88.

Delbeek, Charles J. 1989. Reef aquariums: an introduction. AFM 12/89.

Delbeek, Charles J. 1990. Reef aquariums: coral compatibility; as a reef tank becomes established, corals will grow and require more space. AFM 10/90.

Delbeek, Charles J. 1990. Live rock algal succession in a reef system. FAMA 10/90.

Delbeek, Charles & Julian Sprung. 1994. The Reef Aquarium.

Emmens, C.W. 1986. The natural system and the minireef. FAMA 9/86.

Emmens, C.W. 1992. Coral reefs and miniature reefs. FAMA 2/92.

Fenner, Bob. 1990. The revolution of the mini-reefs. Pets Supplies Marketing 1/90.

Fossa, Svein A. & Alf Jacob Nilsen. 1993. Stony corals; can they grow in a closed reef aquarium? FAMA 9/93.

Frissell, Christopher A. 1981. Living coral in the marine aquarium. FAMA 2/81.

Goldstein, Robert J. 1992. The reef generation; advanced technology and healthy livestock attract customers willing to spend money. Pet Age 7/92.

Guerra, Manuel III. 1990. Compatible fish for reef tanks. FAMA 7/90.

Hemdal, Jay. 1988. Fishes for the home miniature reef. SeaScope Volume 5, Spring 88.

Klostermann, A.F. 1993. Coral growth in captivity. FAMA 5/93.

Moe, Martin A. Jr. 1989. The Marine Aquarium Reference: Systems and Invertebrates. Green Turtle Publ., Plantation, FL.

Riddle, Dana. 1994. Coral nutrition, parts 1-5. FAMA 4-8/94.

Paletta, Michael. 1994. Invertebrate propagation and reproduction at home. AFM 8/94.

Paletta, Michael. 1994. Selecting healthy corals; making the

right choices for your reef tank. AMF 7/94.

Paletta, Michael. 1995. The care and maintenance of corals, parts 1,2. AFM 2,3/95.

Paletta, Michael. 1995. Plumbing the reef tank. AFM 5/95.

Parks, Noreen. 1993. Immortal corals. Sea Frontiers. 1-2/93.

Rasche, Jeffrey A. 1988. Fine-tune the homemade reef system. FAMA 11/88.

Riddle, Dana. 1994. Coral nutrition, parts I-V. FAMA 4-8/94.

Riddle, Dana. 1995. Life, light and lipids; the importance of lip in coral diets, parts 1,2. FAMA 6,7/95.

Schiemer, Gregory. 1995. The reef aquarium; starting from the beginning. AFM 8/95.

Smit, George. 1986. Marine aquariums (mini-reefs), parts 1-7. FAMA 1-7/86.

Smit, George. 1987. The ecological marine aquarium, parts 1-3. FAMA 5-7/87.

Sprung, Julian. 1988 forward. Reef Notes column. FAMA.

Sprung, Julian. Captive reefs. TFH 10/88.

Sprung, Julian. 1988. Reef theory applied to aquaria. SeaScope Winter 88.

Stepanov, Dmitry. 1994. Coral feeding in nature and in the aquarium. FAMA 1/94.

Stuber, Dietrich. 1992. Saltwater reef aquarium technique: a point of view from Berlin. SeaScope Vol. 9, Fall 92.

Thiel, Albert. 1988. The Marine Fish and Invertebrate Reef Aquarium. Aardvark Press, Bridgeport, CT.

Thiel, Albert. 1989. Advanced Reef Keeping. Aardvark Press, Bridgeport, CT.

Thiel, Albert. 1990. The Small Reef Aquarium. Aardvark Press, CT.

Veron, J.E.N. 1986. Corals of Australia and the Indo-Pacific. Angus & Robertson Publishers, UK.

Watts, Mark. 1995. Up to your neck in sand. FAMA 12/95.

Wilkens, Peter. 1976. Mini reef. Marine Aquarist 7(5):76.

Wilkens, Peter. 1989. The reef aquarium- tips on filtration and lighting. TFH 3/89.

History of Reef Keeping, biggest challenges hi my name is Joe and I study aquatics and ornamental fisheries in England I recently went to Aqualink message boards and left a message asking for help with a dissertation I am currently writing on reef aquaria, and someone suggested that you might be able to help me. I need help in researching when the first reef tanks came around <Really... with the popularization of the "Mini-Reef" technology of George Smit in the mid-1980's... though folks had some successes prior to this time (you might look about for the many tries at "A/The History of Aquarium Keeping"... Al Klee's versions are the best IME> and common problems with them. <These are several and diverse. Take a read through our root-web: www.WetWebMedia.com re this... You can gauge what the real problems are by the number of FAQs files by category/issue... Disease, Maintenance, Set-Up, Feeding...> I need to go back as far as possible but have been unable to find much about them, if you could suggest any books or websites or if you have any information yourself that may help me I would gladly appreciate it. yours thankfully Joe Augier
<We will be chatting. Bob Fenner>

Small Marine Aquariums
Book 1: Invertebrates, Algae
New Print and eBook on Amazon:
by Robert (Bob) Fenner
Small Marine Aquariums
ook 2: Fishes
New Print and eBook on Amazon: by Robert (Bob) Fenner
Small Marine Aquariums Book 3: Systems
New Print and eBook on Amazon:
by Robert (Bob) Fenner
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