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Putting on The Brakes:
How Much is Too Much?

By Tommy Dornhoffer

The aquarium hobby has grown by leaps and bounds since its inception. These leaps have largely been made possible by our growing understanding of the needs of our livestock, vertebrate and otherwise. As our knowledge about these animals’ requirements grows, we are able to provide more natural and pleasing conditions for our creatures. However, the dramatic increase in technology and equipment has led to what some consider an alarming overuse of mechanics. I have been an aquarist for only six years, but in that time I have also perceived this alarming trend towards using technology as a panacea to cure our aquariums’ ills. Perhaps the time has come to stop and ask ourselves: Is this wonderful technology really beneficial to our animals?

Let us first consider two aquariums. These reefs are representative of the two opposite ends of the equipment spectrum. One employs immensely powerful lights, enough filtration to deal with a city’s wastewater for a year, and more automation than a small computer firm. On the other hand, the second reef employs only simple lighting, minimal filtration, and some simple devices to make things a little easier to keep up with. Yet, looking at these two tanks, an amateur would not be able to tell a difference; they are both stunning recreations of the coral reef, and both aquarists are to be commended for their skill.

This anecdote illustrates one very important item: the common link among successful and beautiful reefs is not incredible equipment and budgets, but a simple and thorough understanding of biology (and chemistry) and its applications to the home aquarium. In other words, the key to success is not necessarily having the biggest and best equipment but knowing how to use it. That leads me to the central point of this article: Are the wonderful advances in technology truly benefiting the hobby, or are they merely false pathways to success? I will especially delve deeply into three areas: lighting, water motion, and filtration. Of course, any article would be incomplete without mentioning other areas, so I will touch on those as well as mentioning the problems of the currently widespread fad mentality.

A sun in a Bottle: A Critical Look at Developments in Reef Aquarium Lighting

Metal halide lighting is intense - sometimes too intense.  It also covers a limited area with light.  Metal halides shouldn't be considered the answer to all lighting needs, although it works well for  deep displays like this one at the PPG Aquarium in the Pittsburgh Zoo.  Photo by Adam Cesnales

The field of aquarium lighting is incredibly diverse, and it becomes more so with each passing year. It is only natural then, that aquarists make sweeping generalizations in the interest of simplicity. However, few have stopped to ask themselves if these generalizations remain legitimate. For instance, a mindset has developed that metal halide lighting is the pinnacle of aquarium lighting, and is the best setup for any reef. Of course, any intermediate or advanced aquarist knows the flaws inherent in that generalization. While metal halides may be well suited for shallow-water inhabitants or for very deep tanks, there are certainly many applications for which they are not well-suited. That said, metal halides – and most other lighting systems – will work in most situations; it’s simply a matter of optimizing the conditions.

As I said, many aquarists are aware of the flaws in blanket metal halide use (or blanket anything use); but many novice aquarists take the blanket-metal-halide recommendation all too seriously, leading to – in the worst-case scenario – a lighting system that is completely inappropriate for the situation. These situations are actually few and far between, but it is worth noting that mushroom corals – a group which is, of course, a primary beginner coral – have a relatively low ability to adapt to high-light conditions. In most cases, though, the end result is wasted money, and I know of some would-be hobbyists who were turned away because they incorrectly perceived pricey halide systems as an inevitability. With this article, I hope to emphasize that there are other, cheaper ways of achieving our goal (providing conditions for our tank inhabitants to thrive).

This leads me to one of the main points of this little article: Rather than “brute-forcing” aquarium light by applying a general recommendation of extraordinarily powerful lights for all situations, aquarists should seek to use light intelligently, developing a tank plan which includes all aspects of the reef’s future. This should start with the intended inhabitants and build everything else around that piece of information. For instance, if one intends to set-up a reef featuring Mushroom Anemones, he should realize that these animals can do quite well with light and water motion which some would consider to be insufficient. Moreover, anecdotal evidence (oxymoron though that may be) suggests that Mushrooms actually prefer dimmer conditions. Metal halides could work with this theoretical setup, if the aquarist takes some measures to prevent over-illumination, but the aquarist can save money and possibly headache by using a cheaper and simpler lighting system like power compact or VHO fluorescents. Of course, an exceptionally deep tank might require more intense lighting, and that is something to take into consideration. This also brings up one inherent problem with keeping “mixed” reef tanks: it can be difficult to provide conditions that satisfy all the tank’s inhabitants, which often leads to compromises. However, many clever aquarists have found ways to circumvent this problem, but that is really beyond the scope of this article. The point I wish to make is that an aquarist should tailor light to a particular setup, rather than following a sweeping generalization or stocking a tank based on the equipment. I also wish to point out that this is in no way a new or revolutionary idea. Hobby “giants” have been proclaiming this for some time. It is important enough, however, to be repeated at every possible opportunity.

Effects of Too Much Light

Over-illumination has many potential negative effects, including coral bleaching and UV burning. However, many aquarists do not encounter these obstacles, both because of good acclimation practices and the inherent ability of corals to adapt. Instead, there are other actual effects of “light overkill.” Chief among these is increased temperature due to the light, which can in turn lead to bleaching and other mortality. Another potential threat is the increase in algal growth. It is notable, though, that all of these side-effects can be alleviated with a little know-how: temperature problems are corrected by raising the lamps and adding fans (or even a chiller) and many articles and books (all of which are more authoritative than myself) have been written concerning algae control. Why then, did I even mention these aspects of light when they are so easily corrected? The simple answer is that I wish to be complete. Truth is, the biological effects of over-illumination, because they are so easy to correct, are only a small part of the problem (but they are effects which still exist!). The main item which I have a hard time accepting is waste.

I have read many discussion threads questioning whether 250 watts of HQI over a 10 gallon nano-reef is too much. My answer is always the same two-parter: 1) No, it’s not too much, if you raise the light high enough above the tank and watch temperature, but 2) why spend the money when a much cheaper and simpler setup will get the job done just as effectively? Aquarists seem to be of the mindset that more light will always increase health, growth rate, and color. This is true only to a point, and given certain conditions. First, corals need some source of nutrition other than light. Most of the time, this nutrition is provided simply by feeding the fish. However, in tanks with extreme nutrient export relative to import, the corals will actually starve and slowly die (more on that later). It also notable that coral growth rate will “plateau” at a certain point: no matter how much light is added after this point, the coral simply cannot grow faster. The color argument is similar: at a certain point, corals will keep their color; a coral that is naturally brown will not turn green under even the most intense light (though it will at one point turn white). So, lighting overkill won’t necessarily harm the aquarium, but it often represents resources –financial and mental – that could be better applied elsewhere. Novices just starting their wonderful journey should especially take heart from this: you do not need incredibly expensive and complex equipment to experience success.

So, to conclude this section, having extremely powerful lighting is not nearly important as having the correct lighting. Sweeping generalizations recommending incredibly intense light for all applications should be avoided, because not every application requires such lighting, and some applications might even suffer from it. At the very least, the use of very powerful light over every reef represents an unnecessary use of resources. Aquarists with a limitless budget, perhaps, can buy 1000 watt metal halides for everything they create (as long as they take sure to use the light correctly). The rest of us can take heart knowing that that such light is needed in only a small portion of all reef applications.

Much Ado About Something: Water Motion

Another area that has seen significant growth is the understanding, use and application, of water movement in the reef. In stark contrast to my views on lighting though, I think water motion is something that is still often ignored. Many novice aquarists overly concern themselves with appropriate light while ignoring light’s counterpart, water movement. It is impossible to blame them: it seems every other question on an aquarium bulletin board is about light, while questions about water motion are sadly under-represented. However, proper water motion can be more important than lighting in many ways. Of course, the hobby’s understanding and use of water motion could use some examination, otherwise it would not have found its way into this article!

The primary problems with water movement (in my opinion) stem from a lack of understanding of what exactly constitutes “good” water motion. Many aquarists still concern themselves with the turnover rate (that is, how often the tank’s volume runs through a pump). Turnover rate is indeed something to consider with a filter, but it can be very deceptive with simple water movement (i.e. a case where water is simply moving, not going through a filter media). Small tanks especially disrupt the notion of appropriate water movement; they are so small that an “appropriate” turnover rate actually represents less movement than is required. Thankfully, many hobbyists are starting to define water movement in terms of feet per second or similar measures. However, this is something that needs some work, as is providing correct water motion.

Many aquarists try to get incredible water motion using only a few powerful powerheads or strong return pumps from a sump. However, many accomplish this by using only one or two very powerful pumps when many smaller ones actually provide a better “flow field.” What makes a proper flow field is a subject that has received much attention from the experts, so I do not want to go into much detail here. However, it bears repeating that a lot of smaller flow sources are usually (but not always!) preferable to one or two large ones. Of course it is also important to keep in mind what the inhabitants of the tank want. Some filter-feeding corals actually need strong laminar (one-direction) flow. Equipment such as wavemakers and waveboxes are also very beneficial, but budget reefers can again take heart: proper water movement can be provided with inexpensive powerheads. It should be noted though, that all pumps have the potential to increase water temperature. This is something to always keep in mind when planning a tank. [Editors note:  The limitations of using one or two large pumps can be largely overcome by the use of multiple returns or "manifolds".  Plans for these abound on the internet.]

As with lighting, one of the more common problems is providing inappropriate conditions for the tank’s specific inhabitants. Not all corals come from areas of high flow and there are many popular species that do not appreciate extreme currents. An aquarist should always keep in mind what he is planning a stocklist (is anyone else finding that phrase somewhat grating at this point?). It is notable that those corals which require intense light also tend to require heavy water motion (hence these areas of the reef being called “high energy”).

Water motion is in stark contrast to lighting in that it has not yet, in my opinion, reached its peak of development. More aquarists might want to consider shifting their attention from light and redirect it to water motion. However, sweeping generalizations should once again be avoided: not all reefs call for extreme water motion, though that problem is much less pronounced than the similar one with lighting. The one true problem is the use of one or two very powerful pumps to provide the appropriate turnover; the use of such pumps exclusively might actually cause more problems.   

Too Pure? A Look at Common Filtration Practices

Both as an online hobbyist and through my work at the local fish store, I have heard many stories of corals suddenly losing color or even dying after a new piece of equipment was installed. The actual biological processes involved can vary widely, but the bottom line is that this new equipment did one of two things: It either made the water too pure, or it cleared the water too quickly. Although these two items sound similar (and are similar) there are some important distinctions. I will mention these a little later. First, I want to say to all the readers what I say to anyone considering a new filter system,“Don’t fix what ain’t broke.

Maybe if Tim "The Tool Man" Taylor became a reefkeeper, he would choose this enormous skimmer on display at the H&S booth at the Interzoo trade show.  Although this skimmer is designed for commercial use, it certainly is an example of the potential that exists for skimming excess.  And for the keen eyed reader... yes, that is Anthony Calfo in the background and yes, he is giving you the evil eye for even dreaming of putting this skimmer on your 90 gallon reef!  Photo by Adam Cesnales

All too often I have heard or read stories of perfectly healthy reef aquariums collapsing or otherwise being harmed after a radical improvement to a filter system. Many, if not most of these reefs were doing perfectly well and many were quite beautiful. However, the reefkeepers simply could not resist the urge to buy the best and newest filter system. They just knew that their livestock would be even healthier afterwards. In actuality, the massive disruption of the system combined with radically new tank conditions led to problems. That said, there are indeed many tanks that could benefit from the addition or revision of filtration. The key, though, is to move slowly. Just as one would acclimate his livestock for the first time, one must make changes – including improvements – slowly enough to allow livestock to adapt. Almost all of these cases I have dealt with have been ones of mortality caused simply by the conditions changing too quickly. In my experience, one of the most notorious additions is the sudden incorporation of lots and lots of activated carbon.

Activated carbon does two things which have the potential to shock corals. First, it removes trace elements. This should not be a reason to exclude the use carbon. However, the sudden addition of carbon without the supplementation of trace elements (by the way, we should always test the levels of any element which we add to prevent an overdose) can shock livestock. Moreover, carbon can remove some compounds (good and bad) so quickly that the corals, which have grown used to the concentrations of those compounds are shocked by the change in water chemistry. The second thing carbon does is remove coloring agents, making the water clearer. This is a very good thing! However if the water becomes dramatically clearer, the corals will need a chance to adapt to the new light field. Denied this chance as would be the case with the sudden addition of carbon, they can actually bleach. So, what can aquarists do to add carbon safely? Following the advice of many experts, carbon should be added and changed frequently, but in small amounts. It’s a simple solution, but it’s a solution to a problem which is often ignored until it’s too late.

So, suddenly adding filtration can be a problem if it happens too quickly. However, there is another threat to overzealous filtration, one which has only recently made itself apparent. With all the advancements in reef filtering technology and methods, the hobby has actually advanced to the point where people can and do make their water too clean. That statement may sound outlandish to many aquarists but it’s actually a situation popping up more and more. Basically the problem stems from the belief that the reef environment is truly nutrient-poor. However, to paraphrase Anthony Calfo, the reef is not so much devoid in nutrients as it is using them too fast to be detected (what Mr. Calfo and others call “nutrient-concentrated”). There is a massive amount of nutrient exchange occurring on the reef; the nutrients are simply used by reef life (including algae) faster than it is used. This dynamic often occurs in the reef aquarium, but it can be disrupted by the efforts of the aquarist. The combination of nutrient deprivation techniques such as massive over-skimming, large water changes, and bare-bottom methods is all too effective, leading to a tank devoid of all nutrients. This is good for a while, but then the corals start to degrade and slowly die. This happens because no coral can subsist solely on the products of photosynthesis; they must have outside nutrients. In most cases, these nutrients are provided nicely by fish waste, but environments geared toward nutrient reduction are actually ending up with cases of coral starvation. Surprisingly, this war on nutrients is often waged in the name of enhanced color and growth, but it is waged without a good understanding of the complex interplay between nutrients, growth, and color. This is a subject that utterly fascinates me, but it can be fairly intense science, and is beyond the goals of this article. Simply put, no direct correlation has been shown between lack of nutrients and increased color and growth. Certainly, within parameters, improving water quality will improve coral health, but many nutrient-deprived systems are beyond those parameters. [Editor's note:  Another way to understand this problem is to realize that most corals prefer particulate foods like plankton and detritus particles over dissolved organics.  While super skimmers and aggressive filtration techniques will never reduce dissolved organics below those on the reef, they will easily strip the water clean of particulate food items.]

To conclude this section, excessive filtration can have two negative effects. First, if it is implemented too quickly, enhanced filtration can shock corals by abruptly altering tank conditions. Second, extreme filtration can actually lead to true nutrient-deprived environments in which corals simply cannot thrive. Thankfully, only a handful or reefs have encountered the latter problem, but novice aquarists especially should act cautiously when designing a dream filtration system. Unfortunately, many intermediate hobbyists also fall into the trap of “super-filtration,” so they also might do well to keep this in mind. In short, moderation is key.

Are Algae Evil?

Simply put, no. In fact, algae as a group are very good. However, it seems that most aquarists consider algae their arch-nemesis and they go to great lengths to eliminate it. This can lead to some of the situations I described above. Contrary to many views though, algae are an integral part of any reef ecosystem. And by the way, I’m not just referring to the zooxanthellae (symbiotic algae within the coral), free-living algae play a huge part on the reef as well. Why then, you might ask, does it not take over? I would reply: how could it take over, with thousands of herbivores grazing a particular spot in the course of one day? The overwhelming presence of tangs and other herbivores keeps the algae in check. It grows very fast on the reef, but it’s eaten faster. Of course, replicating the massive schools of tangs in the home aquarium can be, well, difficult (if not absolutely inadvisable). However, the dynamic can be replicated by including a relatively large number of herbivores, as long as they are not allowed to starve.

I am of the firm opinion that we should actually cultivate desirable forms of algae in the aquarium. Many books (Reef Invertebrates, for one) espouse the benefits of algae: they absorb potentially harmful nutrients and help to regulate different levels within the system, including pH, oxygen/CO2 , and many others. Of course, incredible amounts of algae growth might require some work to keep them from taking over, but I believe the benefits make the work worth it (especially if herbivores are doing the work for you!).

In summation, the presence of algae should never be considered a sign that something is wrong. Algae will grow in a healthy tank. Period. Our job is simply to make sure conditions (especially the presence of herbivores) favor coral growth over algae growth.

“Aquarists A, B, and C Said I Should Do This. Their Tanks Look Great, So I should Do This…”

I have heard that statement just a few too many times. It’s not necessarily wrong, but one should always know the science behind a particular method before using it. I have been involved in the hobby intensively for six years, and it seems that as the hobby has grown it has developed a nasty “fad” tendency, with each year bringing in a new method everyone has to use or a new coral everyone has to have. The trouble is that many of these “new” things are not at all new, and many people are changing the way they keep aquariums without really knowing the pros and cons of doing so. The latest “craze” seems to be the shift back to bare-bottom reefs. I hesitate to call this a craze, because I do not wish to demean a method which has proven reliable. Instead, I wish to highlight that many self-proclaimed bare bottom devotees have a very poor understanding of the science behind the methods. This leads to people making dramatic changes for the wrong reasons – sometimes even altering successful systems! – and that can lead to disappointment when the method offers no new success to the aquarist. [Editor's note:  Amen!]

Bare bottom tanks are just one new “fad,” and the praise-worthy work of intelligent aquarists has gone a great distance towards educating aquarists on the pros and cons of the different methods (substrate-related and not). Rather than choose a particular method because it seems “everyone is doing it,” aquarists (novice and advanced alike) should consider their goals for their tank and how each method will help them achieve those goals. Most importantly, aquarists should always consider the reasoning behind a particular “fad.” Does it make good scientific sense, or is everyone simply emulating the tank-of the-month from a while back. Of course, emulating a “winning” tank is usually a good way to find success. Just be sure that the methodology is compatible with the aquarium and the aquarist. [Editor's note:  Can I get another Amen!]

I want to close by mentioning one way to sift through all the different ideas out there. With huge aquarium sites like Reef Central, finding good information is not hard; sifting the good information from the bad information on the other hand, is hard. First and foremost, keep in mind that there are as many ways about reefing as there are reefers; anyone who says the method they promote is the only method should be promptly ignored. Even aquarists who claim something is the best for any situation should be treated with some suspicion (though not immediately ignored). In my experience, the best help comes from those who provide not only a suggestion, but also the reasoning and caveats behind the suggestion. My favorite answer, though, is the brutally honest “I don’t know.” That statement, to me, is the ultimate proof of candor and reliability. Finally, get multiple answers for your questions, perhaps even from multiple disparate sites. One aquarist can easily be wrong, but it’s a little more difficult for twenty to miss the mark.


The aquarium hobby has been advancing by leaps and bounds since its inception. However, every advancement must be taken with a pinch of salt (whichever brand you prefer, synthetic or natural). The most important question to keep in mind is this: what benefit does it offer my individual system? It might also be heartening to know that a successful reef does not require incredibly complex filtration, small-tsunami-scale water motion, and sun-rivaling light. Instead, the most important aspect of success is good husbandry, perhaps coupled with a good and sound understanding of the science behind the reef. To close, I would like to bring in one of my favorite sayings about how we should design our reefs: always look to nature; remember that nature has been doing this for a lot longer than we have, and with a lot more success. At the same time, also keep in mind that nature wasn’t doing this with a little glass box and a budget.

Happy Reefing.

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