Bigger is not always better when it comes to reef lighting.
Most corals are highly adaptable to a wide range of light.
Hobbyists with traditional "garden reef" displays
must lean towards the lowest common denominator while compensating
with foods/feeding for photosynthetic species not fully satisfied
by the compromise on lighting.
The topic of this rant
errr, of this
article was inspired by conversations refined from a trip
to the 2004 IMAC. Aquarium conferences and hometown club meetings
are often so invigorating! The time spent listening to presentations,
chatting with vendors, and especially conversing with fellow
aquarists in sidebars (emphasis on bar, in many cases
but productive nonetheless) is priceless. Friends must surely
tire of hearing me sing the praises of these events, but I
strongly encourage my fellow aquarists to attend at least
one aquarium conference or trade show per year. It is one
of the very best ways to network, glean information from other,
often well-traveled or well-read, aquarists, and to advance
our knowledge of the hobby. The money spent really is an investment
in your future success, beyond the gratification of education
and the pleasure of fellowship.
Returning from Chicago, I was moved to put down these thoughts
for consideration of one of the most challenging and controversial
issues in the hobby: artificial lighting. My purpose is not
to try to prove anything; I cannot do that here. I simply
wish to give fellow aquarists pause amid the frenzied purchases
and debates over lighting issues with a reminder that there
is no definitive lighting solution or product to be found.
I'm thinking of the poignant reminder from Dr. Shimek regarding
Science, mentioned again at IMAC, to paraphrase here, "[Science
does not aim to prove anything
but rather, it sets up
two models and disproves one of them]." The issue
of artificial reef lighting really cannot ever be "solved,"
but it will evolve in time.
Too much attention is paid, in my opinion, to obsessive debates
over what is the "best" lamp brand or color for
reef corals. Unless your tank is a natural biotope or specific
niche, the concern may be moot. Coral farmers and public aquariums
for over 20 years now have been growing corals very well under
heavy daylight (industrial) lamps, 5,000 - 6,500 K. Many home
aquarists have also found this to be true, with an emphasis
on warmer colored bulbs when optimal growth of common corals
is the primary interest.
Manufacturers and researchers continually
spend an enormous amount of time and effort trying to improve
lighting technologies. Similarly, aquarists spend an extraordinary
amount of time trying to research, argue, defend, or determine
what is the "best" lighting for a given reef aquarium.
To all, I say, "Keep your eye on the prize." (a
favorite phrase from another mentor of mine, the inimitable
Bob Fenner). What is it that we are trying to prove? The goal
in lighting your photosynthetic creatures is not to have optimal
but optimal health of the animals themselves,
by whatever means. Those means cannot be satisfied by summarily
saying, "if you want to keep x coral, then you should
have x lighting." It just does not work that way. The
three dimensional environment of an aquatic system is influenced
by many factors. Does anyone truly believe that any standardized
lighting scheme could be "perfect" for the random
and various organisms we collect from the world's reefs when
we not only mix specimens from different niches or biotopes,
but different oceans?
Case in point, lets say that you get an established coral
from an aquarium with known hardware (lamp type, color and
wattage) with a known measurement of light (in lux). Even
by having the same type of hardware at home and placing the
coral at a depth with the same lux reading, you still cannot
guarantee that the coral will get the same illumination. The
quality of light delivered can be affected by the age and
temperature of a lamp, for example. And the penetration of
water at any depth can be affected (filtered, refracted, etc.)
by turbidity, clarity or action of water at the surface. Thus,
the placement of x coral at a depth that has the same reading
of y lux, under the same brand and type of z lamp, is still
not guaranteed. We are at the mercy of some very common realities
of aquarium-keeping here. What if tank A has an older bulb
but better water clarity (daily ozone or weekly carbon use)?
If tank B has a newer bulb but worse water clarity (i.e. more
discolorants) can we succeed in getting the same lux reading
at a given depth? Yes. Will the quality of light be the same?
No. Is it a big enough difference to be concerned about? Perhaps...
or perhaps not. This clumsy analogy speaks to the limitations
of using lux, for example, as a unit of measure that so many
aquarists beg for with the hope of bringing some fact or science
into the debate about reef lighting. I think that if I hear
one more hobbyist complain that there is no book or reference
listing the "necessary" lux for all of the beautiful
corals he wants to keep, I will laugh myself to incontinence.
There are other factors to consider beyond lux readings.
Divert some of your energies away from debates about
the "best" reef lighting, and instead to issues
such as the physical delivery of light. Of special concern
is maintaining optimal water clarity by regular carbon
or ozone use and weekly cleaning of dust and debris
from lamps and lenses. There are also some very novel,
if not effective, methods for mounting and moving light
systems, which are worth experimenting with.
Issues of water clarity and turbidity instead
are grossly underestimated in my opinion. You can test for
and quantify this with your systems easily - read on. In all
my travels, and for all the aquariums I've seen through the
years, it still surprises me to see expensive lighting systems
trying to punch light though dirty lamps with water spots
on them, through lenses and glass or acrylic covers with dust
and salt creep, or simply through turbid or unclear water.
Problems with turbidity specifically are relatively uncommon;
few tanks actually have regular and persistent problems with
suspended particulate matter. For those that do, know that
it is a severe impediment to the penetration of light at depth.
By comparison, we can look to some of the thorough research
done on UV sterilizers to determine their efficacy (it is
critical to pump only highly polished water through these
units if they are to be effective at all). A pervasive problem
that aquarists commonly face is water clarity, or discoloration
to the water. How many hobbyists would you guess use ozone
full-time to maintain optimal water clarity? How many aquarists
change small amounts of carbon weekly instead of monthly (to
prevent light shock or stress)? Some folks use no chemical
media or ozone at all! I'm not saying that you need carbon
or ozone to maintain optimum water clarity, but short of large
and frequent water changes, there really is no practical alternative.
Although your water may not look particularly yellow or discolored,
rest assured that even a slight discoloration after a few
weeks can reduce the penetration of light. If you have any
doubts, just buy or borrow a lux meter and take a reading
before and after an application of ozone or carbon. Its ironic
that many aquarists spend so much money on fixtures, lamps
and electricity, yet fail to keep up with simple maintenance
tasks to maximize the use of light produced!
The issue of cleaning lamps, lenses and tank covers should
be similarly obvious. Yet, in our busy lives, we often forget
to faithfully maintain these, and subsequently handicap our
light systems and photosynthetic creatures. I promise you
that the reduction of light from any of the above mentioned
obstructions is a far greater issue than the often subtle
differences between a few months of age on a lamp due for
replacement or even the choice between similar colors/brands
of many bulbs. If you want to get the most "bang for
your buck" with aquarium lighting, focus on maintaining
your hardware and worry less over the search for magical lamps
and measurements. Clean all lamps and lenses weekly for best
results and minimal disturbance or shock to the illuminated
Having read this far, you might easily
gather that I am not a big "fan" of using light
meters. On the contrary, I use lux and PAR meters and strongly
encourage most serious aquarists to buy or borrow a meter
to learn fascinating and important information about the delivery
of light. I preach to most every aquarium club I visit that
they should invest in a unit for the membership to share for
renting or lending out. Readings taken on new and aging lamps
(reference points and tracking their performance degradation)
can give an indication of when its time to replace bulbs.
Non-believers in carbon use can find new appreciations in
what was previously thought to be clear aquarium water. And
the impact of just a little bit of dust or debris on lamps
and lenses can really be underscored with a check of light
intensity before and after a cleaning. Above all, though,
use a light meter merely as a guide and not as a rule - much
like an ORP meter. Redox (ORP) and light meters will help
an informed aquarist tune and tweak his husbandry habits for
better success overall - no more, no less.
It funny, but I still hear reservations to this day from
aquarists and distributors who have fears or concerns about
greenhouse grown corals acclimating to artificial lights.
With all due respect, the logic behind this line of reasoning
(or lack thereof) baffles me?!? How is it that corals collected
from the wild, as most still are, differ from corals grown
locally or regionally in a greenhouse? No doubt, wild corals
stressed from collection and the rigors of import are less
prepared to acclimate to artificial lighting than are soundly
established, domestically produced livestock. This mention
of farmed corals is a slight digression, but nonetheless still
speaks to the real underlying issue: the adaptability of coral
to a wide range of light. Folks with traditional "garden
reef" displays must take advantage of this to have any
hope of long term success. With a wide mix of species having
different lighting needs and preferences, a hobbyist must
lean towards the lowest common denominator and hopefully will
not include terribly incompatible tankmates with grossly different
needs or tolerances for light. With species requiring higher
light intensities, the aquarist can compensate for the lack
of light, and production from zooxanthellae, by extra feeding.
Interestingly, the opposite approach does not work. That is
to say, for example, corals that derive 75% of their nutrition
from the products of symbiotic photosynthesis cannot be compensated
for a lack of food (the remaining 25% of their daily nutrition
from organismal or absorbtive feeding) with "extra light"
(neither in duration nor intensity). Most all corals need
to be fed regularly!
Unless one has a magnificent 20,000 gallon reef aquarium
like the jewel at Atlantis in Riverhead, NY, there is
no need for most aquarists to have banks of halides
in sufficient numbers to dim the neighborhood's lights,
melt live rock and make the sun envious.
Let's divert some of our energy from concerns,
and especially debates, about the "best" artificial
lighting and focus instead on the animals - not just the hardware.
So many of the creatures we keep occur over a very wide range
on reefs by a remarkable scale of magnitude (like Catalaphyllia
elegant corals and some acroporids separated by more than
20 meters)! Yes
the same species, but profoundly different
exposure of dispersed colonies to light. In such circumstances,
the arguments over specific measurements of light becomes
particularly moot, and the value of improved feedings (to
compensate for deficiencies in light) and water flow (for
better health/growth) become more apparent.
In a phrase, I think too much attention is paid to lighting
issues. With the availability of several well-established
lamp brands and types (time tested and favored by a consensus),
I'm content to use and recommend bulbs such as Ushio, Aqualine,
Radium and Iwasaki without obsessing too much over minutia.
Furthermore, with most aquarists keeping "garden reef"
tanks with unnatural mixes of corals (high species numbers
and concentrations), expectations for optimal results with
all specimens in the display is plainly unrealistic! There
are some generalizations about light that a majority of aquarists
can (maybe) agree upon. Take them as my opinion and nothing
else. Lamps with a higher PAR rating and color closest to
daylight (basically the 6500 K bulbs) tend to support the
fastest growth among commonly kept species in the trade. Deeper
water zooxanthellate cnidarians with pigments that fluoresce
attractively (i.e., corallimorphs, Fungiids and other so-called
LPS species) seem to keep very well under bluer lamps (20,000
K bulbs). And the ever popular (with good reason) 10,000 K
lamps seem to offer a nice balance between growth and aesthetic
color for most popular species. Again, these are only gross
yet the overwhelming majority of aquarists
are not housing biotope displays, and thus have no right or
reason to expect a tailored solution for lighting challenges
over garden reef displays.
Finding good reef aquarium lamps is not difficult.
Data from manufacturers and independent studies
alike are easily found on the Internet and elsewhere.
If you have a mixed garden reef display, then
your choice is easy - buy most any reputable brand
like Ushio or Iwasaki, because no lamp in existence
could possibly optimally support the random and
various mix of corals in everyone's tank. Improve
coral growth otherwise with improved feeding and
So we come back again to the issue of adaptation,
or acclimation. It's the dead horse that I'm trying to beat
here. The recurring theme: please, please, please - quit obsessing
over the search for the "Holy Grail" of reef lighting.
It does not exist. From the advice above and an intelligent
consensus from other sources, pick a reputable light system
from an established company and be content with your choice.
We can then focus our energies on better ways to acclimate
corals. For many years I've been recommending a favorite technique
called the "screen method." This is not rocket science,
my friends. Rather than start new corals at the bottom of
an aquarium and work them slowly up the reef to their final
destination, as has been the tradition, we take a more direct
approach. Place new corals, anemones, plants or algae in the
preferred spot in the display from the very start. Atop the
aquarium cover, or upon improvised support such as PVC rods,
place a stack of plastic screen or hardware clothe (bulk flyscreen
used for windows or doors) cut in squares that are slightly
larger than the footprint of the new organism that we are
acclimating. About a dozen sheets will be enough. In the shadow
of this screen, the new coral can adjust very gently to new
lighting by the removal of a single sheet of screen every
other day or so for a couple of weeks until all sheets have
been removed. Any concerns about deficiencies in light can
possibly be allayed with regular feedings or other provisions
(refugia, adequate dissolved organics, sand stirring, etc.)
for our filter feeders. There are indeed many other novel
ways of acclimating corals worthy of a separate discussion
altogether. A gentle acclimation is particularly important
for recently imported corals. Although they may have come
from a place on the reef with sunlight much brighter than
your artificial lamps, the extended time in holding and transit
in dim light or darkness from the point of collection to the
final destination (your merchant's tank or your home aquarium)
was likely a week or more. Light shock is often the final
insult to stressed and "road weary" corals. New
corals need to be handled conservatively and a gradual acclimation
to bright reef lights is always a safe approach.
These suggestions and thoughts presented here are but one
man's perspective. If I have given you pause to reconsider
habits and husbandry, or relieved some anxiety you may have
had over the expensive and important components of lighting
for your reef aquaria, then I have succeeded. Best of luck
to you in all of your endeavors, Anthony Calfo.