Mything the Point, Part Three: Conclusion

This article represents the last part of a three part series covering the many and widely variant sources of reef fallacies and suppositions. As I mentioned at the end of the last part in the series, the list I have made here is by no means exhaustive, and one could practically continue with such a listing for a very long time, and for a great many words. I fully envision a whole new series of articles as being possible within a relatively short period of time. This is unfortunate, but stems largely from the fact that reef keeping is still a relatively new practice, and there are vast areas yet to be understood more completely.

It is fortunate that as the numbers of aquarists increase, so do the number of significant findings associated expressly with aquariums. Using information based on the biology and ecology of natural communities, physical and chemical canons, and general scientific bases is a strong start. Yet, there are idiosyncrasies and specificities that occur in aquariums that are unlike anything found in nature. As such, more direct, careful, and judicious experimentation will quickly lead to the elucidation of many of the artifacts of closed system aquaria.

Myth 14: Microbubbles are to be avoided.

Many aquarists go to some considerable lengths to baffle sumps and pump flows to prevent small bubbles from being returned into the display tank. It has been suggested that such bubbles represent an irritation to fish, corals and other invertebrates and that they should be avoided. To be honest, I am unsure from where the origin of this perception came. However, it is untrue. Even the name is inaccurate… the prefix "micro" would refer to bubbles too small to see.

The onslaught of bubbles from this oncoming wave should make it apparent that
corals and coral reefs exist just fine with the presence of air bubbles in the water.

Small bubbles are very common in tumultuous reef environments, and areas where waves break are often dense with both reef life and small bubbles. In addition, in tanks and on reefs, many bubbles of various sizes, including true "microbubbles" are produced by photosynthesis, and this is especially the case in highly illuminated environments. In my own aquaria, a constant rise of bubbles, especially in the afternoon, are produced by various corals and algae in even some of my less-illuminated systems. Larger bubbles frequently get sucked into pump intakes, and are chopped up to even smaller sizes and distributed throughout the tank. I won't even begin to discuss the massive numbers of bubbles produced by various surge devices. These water motion devices have great benefits in aquaria, and even as anecdotal aquarium observations, I have never seen anything disturbed, irritated, or harmed by the rush of bubbles.

Potential: Relatively harmless. Neither bubbles nor the lack of them in a tank is likely to endanger the health or survival of organisms.

Distribution: A patchy, but common belief.

Myth 15: Concepts about Nitrification, Stocking Orders, and the New Tank

I had owned Nilsen and Fossa's The Modern Coral Reef Aquarium for several years before I noticed one particular photo in that book that is exceptional. It is a nice reef tank, but by no means what most would consider to be a "show winner." However, it is unquestionably a show winner, for it is a reef aquarium that grew solely from live rock. If there is one universal answer to the question, "What does it take to make a successful reef aquarium," the answer is patience.

For those who have not read one of the threads stuck at the top of The Coral Forum, I offer this revised version of that information. A tank begins without populations of anything. Live rock typically forms the initial basis of the biodiversity. Virtually everything is moderated by bacteria and photosynthesis in our tanks. So live rock is the substrate for these microbes and processes, and also has a lot of other life on it. How much depends on a lot of things. Mostly, marine animals and plants don't like to be out of water for a day, much less the many days to sometimes weeks that is common during live rock collection and shipping. So, assuming that existing rock from a tank is not being used, nor the well-treated aquacultured rock, most live rock is either relatively free of anything alive, or has a few stragglers and a whole lot of stuff dying or about to die because it won't survive in aquariums. From the moment it is added to the aquarium, a deficiency has begun that likely worsens over time. Coralline algae, sponges, worms, crustaceans, echinoids, bivalves, algae, chordates, and all manner of other taxa will begin dying, many of which are within the rock and would never be seen. All this occurs without mentioning the algae, cyanobacteria, and bacteria, most of which is dead and will decompose, or which will die and decompose. Life will return to some degree, as we all have experienced, but not until death and more death have occurred. However, this process is where it all begins.

Bacteria grow really fast, and so they are able to grow to levels that are capable of taking up nitrogen within a typical cycling time of a few weeks to a month (or so) to levels where ammonium and nitrite are not measurable by hobby test kits. Most people assume, wrongfully, that the tank is now "cycled." However, the fact that ammonium and nitrite are no longer easily measured does not in any way imply that the tank is truly cycled, mature, stable, or in any way able to easily support life in the form of new additions. I will discuss this more in the passages below.

If one realizes the doubling time of many bacteria, one would know that within a month, there should exist a tank packed full of bacteria with no room for water. That means something is killing or eating bacteria. It should also be realized that if the tank has decomposition happening at a rate high enough to spike ammonia off the scale of a hobby test kit, there is a lot of food for bacteria that consume this material, and far more than will be present when other things stop dying off and decomposing. So, bacterial growth may have caught up with the level of nitrogen being produced, but things are still dying. An aquarist simply "tests zero" for ammonia because there are enough bacteria present to keep up with the nitrogen being released by the dying organisms. It does not mean things are finished decomposing.

Now, if things are decomposing, they are releasing more than ammonia. Guess what dead sponges release? All of their sequestered toxic metabolites. Guess what else? All their natural antibiotic compounds and these will prevent some beneficial microbes from doing very well. The same occurs with the algae, many other invertebrates, the cyanobacteria, the dinoflagellates, and others. Suffice to say that this death and decomposition is going to take a while to complete.

Through the initial periods, there will be a tank packed with some kinds of bacteria, probably not much of others. Eventually, the massive death slows and stops. Now, what happens to all that biomass of bacteria without a food source? They die. So, another cycle of decomposition begins, and this back and forth process will continue for a while until equilibrium is reached. I say equilibrium, but that is a relative term since reproduction and mortality is a constant process in our tanks, as are "mishaps" and the relative size of the pendulum swing will depend on the reproduction and mortality rates, and biomass of the organisms involved. Still, the new swing of dying bacteria also has antibiotics, toxins, and other substances released when they die. But, the die-off is relatively slow, and is relative to the loss of nutrients, and there is already a huge population present. The result to the aquarist is that they never test positive for significant levels of ammonia. "The water tests fine."

Furthermore, denitrification is a slow process. Yet, all these back and forth swings are happening... every time, they get less and less, but they keep happening. Eventually, they slow and stabilize. What's left? A tank with limited denitrification and a whole lot of other stuff in the water. Who comes to the rescue and thrives? The next fastest growing groups... cyanobacteria, single-celled eukaryotic algae, and other protists. Then, they do their little cycle thing. And then come the turf algae. Turfs will soon get mowed down by all the little amphipods that are suddenly springing up because they have a food source and will reproduce rapidly. Perhaps the aquarist has purchased some snails by now, and maybe a fish. All too often, the fish dies, because while it may not have ammonia to contend with, it has water filled with chemicals we can't and don't test for. Beginning aquarists may also have been too frugal with their purchase of important equipment like lights and pumps, and may not have yet figured out the important alkalinity test, so pH and O2 are probably swinging wildly at this point. Tests for phosphate are also usually an afterthought, often purchased only when algal biomass becomes uncontrolled.

No one wants their tank to look like this!

As a few more months pass, the algae successions begin, and eventually there exists an algal biomass that handles nitrogen along with the bacteria, and the aquarium keeper has perhaps stopped adding fish for the time being because they keep dying. Maybe during this time they started to visit internet forums, read books, begin learning more, and get the knack of the tank at least a little bit. They have, unfortunately, probably added a smattering of "fix-it-quick" chemicals (that probably didn't help any, either). Also, there are probably two further scenarios; aquarists that are scared to add corals in their "new tank of death" that would actually help with the photosynthesis and nutrient uptake, or aquarists that have packed in corals (most of which aren't tolerant of the "tank of death" conditions). Equally common are aquarists who stock their tank haphazardly without consideration of whether or not the habitat present is suitable, but that is a topic for another article. What may be relevant, however, is the common pattern of stocking corals according to "hardiness" over time. Initially, soft corals of the family Alcyoniidae (leather corals), corallimorpharians (mushrooms) and zoanthids are the first species to be purchased. The rationale for most is that they plan to stock with easy corals and then "move on to stony corals." The problem with the rationale, seemingly logical though it may be, is that success of these type species may make the tank even more incompatible for the success of stony corals because they are typically superior competitors (usually by secreting waterborne chemicals that inhibit or kill the stony corals or by the capability of overgrowing them).

A host of "fix-it-quick" products exist to help new aquarists through early troubled times.

About a year into the experience, the sand bed is productive and has stratified, water quality is relatively stable, and the aquarist has probably bought at least a few more powerheads, understands water quality a bit, some corals, coralline algae and other algae are photosynthesizing well, and the tank is becoming "mature." That's usually when fish stop dying and corals start to live and grow.

Ecologically speaking, this is successional population dynamics. Its normal, and it happens when there is a hurricane or a fire or other disturbance. In nature though, there are pioneer species that are eventually replaced by variably persistent "climax" communities. We usually try and stock tanks immediately with climax species and find it doesn't always work. The preceding passages illustrate what good approximations reef aquariums are of mini-ecosystems. Processes and events tend to happen much faster in tanks, but this should be expected given the number of organisms per unit area. Our "climax community" happens in a couple of years rather than a couple of centuries, but it happens nonetheless.

After all the descriptions above, perhaps the "myth" that is the focus of this article has been forgotten. This section actually covers several myths: the myth reflected by the statement "my tank is cycled" or "my rock is cured," and the myth of the statement "my water tests fine." The truth is that the tank is never cycled, the rock is never cured, and water that "tests fine" may be variably fine in terms of one or a few parameters that may or may not be ultimately important for the survival of the creatures we keep in aquaria. As a supplement to this section, I offer some advice (and "advice" is not something I am overly fond of providing because it tends to be limiting to the viewpoint of the person giving it!). I offer the words from a slide I have given in presentations and am frequently requested to print or email after I have shown that slide to a group. The following is how I would suggest new tanks be initiated:

Potential: Always serious. Mortalities early in the life of an aquarium can usually be prevented. At the worst, these early misconceptions lead to long-term problems with tanks, have medium-term direct effects, and short-term mortality associated with them. Often, prevention and understanding would alleviate the issues, and surely many aquarists leave the hobby because of the many problems that happen early on with new aquarium set-ups.

Distribution: Nearly universal. Being patient with a new tank is almost an exercise in futility that requires restraint. Generally, only those who have kept reef aquariums prior to establishing a new one are likely to take the steps required to ensure the best development and success of new set-ups (and this is still comparatively rare). Ultimately, the development of a tank by the actions of an aquarist who "goes slow" will far outpace those of aquarists who lack the patience and foresight.

Many years down the road, another condition might occur when the system is too mature; this is sometimes called "old tank syndrome." What happens in this situation is that conditions have become somewhat stagnant, or populations that are present are either limited by some resource or are the only species capable of persisting in the relatively non-fluctuating environment. This happens in nature, too. The well-known example of a forest fire reinvigorating the system is true. Equally true examples occur on coral reefs where the intermediate disturbance hypothesis is an experimentally favored explanation of why coral reefs maintain very high diversity; they are stable, but not too stable; require storms, but not catastrophic ones; need predation, but not a giant blanket of crown of thorns starfish; tolerate mortality, but not mass coral bleaching or the near total loss of key herbivores.

Myth 16: Corals will regrow over dead areas of their skeleton.

This one is only partially a myth. Living coral tissue may indeed grow back over skeleton that has been exposed from partial mortality of the colony. However, there is no real reason to suspect it will, and unless there are small bits of tissue still living inside the apparently dead skeletal corallites, the process is not as it may appear if exposed areas are eventually recovered by living tissue.

Coral skeletons form part of the reef framework. Once they die, for whatever reason, the skeletons are eroded and become encrusted by other life, including other corals. With partial mortality, living parts of a colony have no "attachment" to their old vacant corallites, figuratively or literally. It is not a preferred place for them to live and grow. The coral tissue that remains alive will simply keep growing and calcifying, upwards and outwards. Whether or not it grows outward and recovers its own dead skeleton is mostly a matter of how favorable it is to grow in that direction. Generally, at the rate corals grow, the exposed skeleton will have long been covered with other organisms vying for space before the coral can grow over it. To retake that skeleton means that some sort of competition will be required. In some cases, it may simply be overgrowing coralline algae. But, if it means overgrowing more competitive organisms, the remaining colony may just grow off in other more energetically favorable directions. In fact, this is more than likely what would happen.

Even if the coral does recover its own dead skeleton, the polyps that grow over it will not take up residence in the old corallites. They will create their own new ones on top of the old ones. This type of regrowth can be used as a proxy of environmental events that caused partial mortality to a colony, and cores taken from old colonies usually show a change in the primary axis of growth when the skeletal core is examined in cross section.

As I stated in my first article in this magazine, partial mortality of a colony is nothing to be concerned about, and whether or not it ever becomes recovered with the same coral's tissue is not really a concern so long as the remaining polyps of a colony continues their growth somehow. After all, none of us are really too concerned about the appearance of all the calcium carbonate that lies underneath the living veneer of tissue, either. Time heals all wounds, even in coral colonies.

Potential: Minimal in terms of the health of the tank and the coral colony.

Distribution: patchy but common statement and belief throughout aquarium circles.

Myth 17: You can never skim a tank too much.

Yes, you can. Far too many works have dealt with various aspects of protein skimming. I still feel there is too little information on exactly what, how much, and how effectively foam fractionation affects various components of the water column of reef aquaria. For the most part, protein skimmers are employed as water quality control devices to maintain low levels of organic and some inorganic materials, notably compounds containing nitrogen and phosphorous commonly linked to degraded water quality not conducive to the growth of many reef species such as corals. Whether or not they are used secondarily for other questionably useful purposes such as elimination of toxins or increasing oxygenation is another matter. My point is that once nutrient levels are low and conducive to a healthy aquarium, and until other secondarily important aspects of protein skimming are experimentally validated and quantified, any skimming over that required to maintain low levels of organic and inorganic pollutants is overskimming. Why? Because if the water is cleared of those things that are detrimental, it is also likely to be equally cleared of things that are beneficial. Given the now well-recognized limitations of providing large amounts of food without a corresponding decrease in water quality, skimming as little as possible while maintaining the aforementioned high water quality is only pragmatic. There is no advantage to a constantly stripped water column in all but a very few specialized situations.

If I were asked what a solution might be, I would propose the following. Use the most efficient skimmer possible and one that is capable of maintaining high water quality when used constantly. Assuming that they do provide some amount of oxygenation, even if minimal, I would then begin shutting off the skimmer during the day for a few hours and measure tank condition visually and through testing for several weeks. If water quality is maintained, I would increase the number of hours the skimmer is off, and wait again, continuing this process until the maximum number of hours is reached where water quality and tank health remains the same without the use of the skimmer. I would also opt for daylight discontinuance since oxygen is less of a problem when photosynthesis is occurring, and since most aquarists tend to feed fish and other products like phytoplankton during the day. This way, residual foods will not be removed for at least several hours. Some aquarists may even find that they can discontinue skimmer usage entirely (I think this likely, especially if activated carbon is employed).

Potential: Minimal to serious. In the best cases, continuous skimming results in relatively healthy tanks that are considered successful by most standards. In the worst cases, organisms perish because of the lack of available foods in the water column. In most cases, the results are a "sterile" looking tank with little alive but corals and coralline algae. Corals tend to appear weakened and, for lack of a more accurate description, not robust.

Distribution: Extremely widespread. There are many who employ alternate means of tank filtration, and these are usually the same people who appreciate the obvious differences in allowing more material to remain in the water column without compromising water quality. Foam fractionation use is both desirable and extremely widely employed, but as with other things should be employed properly and with a judicious purpose.

Myth 18: My aquarium is a reef-crest type tank.

Sorry, but I very much doubt it. There are many reef crests that are occasionally exposed to widely variant conditions that range from onslaughts of rushing water to absolute stillness. But, the typical fringing coastal, atoll, or barrier reef crest is someplace humans don't usually go or can't negotiate. Why? Because of the imminent threat of serious personal injury. It only takes a very small wave breaking over shallow corals to toss a human of considerable weight like a leaf in the breeze. If one snorkels near a reef crest, it is a constant physical negotiation to keep from being smashed onto rocks and coral. A continuous body adjustment as one is lifted up and down and side to side, consisting of dexterous twists and brief sprints, is required to be in this area. Even fish adjust their swimming behavior. As waves approach and cross an area, small fish trying to maintain their position or territory swim as hard as they can in one direction, only to quickly stop as the wave passes. Other fish take shelter in corals and rocks each time a wave passes. While not on the reef crest, nearby stiff-bodied invertebrates strain against the water forces, bent sideways every few seconds. Softer bodied creatures, only existing in more protected nooks alee of wave action are pummeled, and it amazes and fascinates me that they survive the continuous unrelenting barrage of wave action. On the reef crest itself, it is very unlikely soft bodied sessile animals will exist. It is a very stressful, violent, inhospitable and relentlessly tiring place to live.

Many aquarists think of reef crests as being areas where many species of Acropora and small polyped corals are found. In fact, only some species are found there and the greatest diversity exists quite a bit deeper. Staghorn corals are not found on most reef crests because they would be shattered. Table corals are not found on reef crests. They would be uprooted. Only the most robust growth forms exist there, and colonies tend to be small. On many reef crests, the force of water and the particles in it are too erosive and abrasive to allow for any soft tissues to exist, and corals are excluded. In such places, coralline algae and perhaps encrusting Millepora are providing the cover of the reef crest.

I have never seen a home aquarium where I would feel physically in danger were I able to get inside of it. I have never seen a pump that would toss me around like a leaf. I have never seen any tank anywhere that in anyway resembles a reef crest. Even small crafts with outboard engines have difficulty maintaining a position anywhere near a reef crest, and I suspect no one has an aquarium that would thwart a 40 horsepower Johnson outboard. To provide conditions even like those at five to ten meters depth in an aquarium would still be quite a feat.

Potential: Minimal to serious. In most cases, this myth is just a misconception of the nature of both the reef crest and the tank. It won't do much harm. However, if one perceives their aquarium to be a reasonable facsimile of a reef crest and attempts to maintain animals found on or collected from a reef crest, failure might be the result.

Distribution: Fairly common, especially among non-divers and enthusiasts of small-polyped corals.

Myth 19: To propagate corals, one should break or cut off a branch or section, and then apply glue or affix the broken fragment to new substrate.

Coral propagation is really quite easy. But, as I have said many times, these are not plants. Perhaps the use of terms like "stalks" and "branches" and "photosynthesis" confer this notion. But, one should not "plant" corals with the healthy parts up and the broken edge in the dirt, as though this was the "root area."

The goal in propagation is rapid attachment with low mortality. Broken tissue is an injury, and injuries are more prone to get infected. Reef substrate is covered in biofilms and other microbes. The substrate also has reduced oxygen and water flow, and is a site where other organisms may engage in competitive or predatory behaviors. Finally, injured tissue must undergo repair before growth is initiated. The only helpful attribute of the "coral planting" method is that the tissue edges are often sealed by cyanoacrylate (super glue) that minimizes chances of infection. Epoxy putty, however, confers much less of an advantage since the glue is much less adhesive to mucus-covered tissue unless very diligently applied.

Providing the maximal amount of healthy tissue against substrate encourages rapid attachment and reduces the chances of infection and mortality. Placing cut edges in water flow encourages healing and reduces the effects of the detrimental attributes of substrate. Try it. I suspect all the little "pine seedling" propagators out there will soon change their ways.

The photo above left shows the "wrong way" to mount corals. The photo above right shows the right way to mount corals.

Potential: relatively minimal. Corals are tolerant animals, in general, to fragmentation and the majority of fragments even affixed in the wrong way by "planting them" will probably survive. Some that do not survive may have survived if affixed by a different method more conducive to regeneration. The biggest potential detriment is the increase in the time it takes for fragments to reattach and in reduced growth potential.

Distribution: Extremely widespread. Almost everyone, including those who propagate corals "professionally" are mounting corals incorrectly.

Myth 20: The aquarium hobby has little to no impact on reefs.

In some cases this is true, in some cases this is untrue, and in most cases we just don't know what our impact is. But, in some cases the aquarium trade has caused significant declines in targeted species. The solution is to be aware of what wild collected species are common, and which are not, and to always purchase sustainably collected, maricultured, or aquacultured stock when possible. I look forward to covering this topic in much greater detail in a future article.

Potential: Devastating to some species, of minimal concern for others.

Distribution: This is a widespread conception that is unfortunately based largely on supposition and the hope that the statement is actually true.


This series has been a very incomplete look at some of the more pervasive myths that are part of the community of people keeping marine and reef aquaria. In the first part of the series, I began with a somewhat lengthy discussion of critical thinking and definitions of terms like "anecdote."

Being skeptical and critical in our assessment of information in this hobby is imperative. The facts are few, the opinions are many. The general level of understanding is low, the data to support our observations scant, and what persists is the all-to-common willingness to support our own shortcomings of knowledge with those spoken and written by those equally or sometimes more in the dark than ourselves.

We must listen more, think more, read more, and speak less. At the very least, we should temper our enthusiasm and excitement by prefacing our supposed truisms with really helpful modifiers; could, should, might, probably, seems to, in my observations, in my opinion, and looks like will more credibly explain the immense number of unknown possibilities that express themselves regularly to us through the windows of our tanks. In time, we might even be able to say assuredly "my water tests fine" and quantify how "my tank never looked better."

Link to Part One, Part Two

If you have any questions about this article, please visit my author forum on Reef Central.


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Mything the Point, Part Three: Conclusion -