This article first appeared in the vol. 3 No. 5 1990 issue of Atoll

Fluorescent lights are quite handy to use since they are easily
installed and maintained by the average hobbyist, and they are less
expensive. There are so many different types of bulbs available that
a hobbyist, who takes the time to do the research, can easily develop
a combination that will duplicate the exact spectrum they want. The
intensity of some fluorescent combinations can even match those of
most HQI sources, especially when used in conjunction with properly
designed fluorescent lighting reflectors. This invariably means using
high output (HO) or very high output (VHO) lamps since using the
regular output bulbs would require so many bulbs that you couldn't
fit them all above a tank. When using HO and VHO bulbs you must be
aware that some of these can also produce potentially harmful U.V.
and should be shielded appropriately. One of the problems with
fluorescent light sources is that both their intensity and spectrum
change with age. This is especially true of HO and VHO fluorescents.
The decrease in intensity could cause reduced growth rates of both
corals and algae, while the spectrum usually shifts towards the red
end which can lead to breakouts of undesirable algae. These bulbs
should be replaced at least once every six months, even more
frequently if reef-building hard corals are kept. The accepted
recommendation for fluorescent lights has been to use a combination
of Daylight and Actinic type bulbs, primarily to ensure a spectrum
heavy in the end blue and low in the red (Burleson, 1987). However,
there are now a number of fluorescent lights that make various claims
about the suitability of their spectrums for reef aquariums. One
must, of course, use one's own judgment and rely more on facts than
advertising copy. Try to obtain spectral output charts for the bulbs
you are interested in as well as information on their colour
temperature and colour rendition. Look for bulbs with high Kelvin
ratings (6000 K), good colour rendition and an efficient lumen to
watt ratio. Moe (1989) gives a complete listing of the more common
fluorescent lamps, including the above information. Pay special
attention to the amount of U.V. radiation produced and take necessary
precautions. One may have to bypass the distributor and go directly
to the manufacturer to get the information. If no one will supply you
with the information you need, then look for other bulbs.

I have seen many beautiful tanks lit by both types of lighting; HQI
and fluorescent. I do not agree with those who say success with hard
corals cannot be attained with HQI lighting for I have seen
otherwise! HQI lighting gives excellent results with both soft and
hard corals WHEN USED PROPERLY. I have seen aquariums that have
beautiful, vibrant hard coral growths under HQI lighting and under a
combination of HQI and intensely blue bulbs such as the Philips
Actinic 03 bulb. Leather corals can grow to fantastic sizes with HQI
lights and with HO and VHO fluorescents. The key seems to be a
proper combination of intensity and spectrum. Providing intensity
for simply intensity's sake is counter-productive if the proper
spectrum is not provided also. When the proper spectrum is provided
most organisms do quite well but if the intensity of that spectrum is
increased then their growth rate increases substantially.
Fluorescents are cheaper but their frequent replacement time may make
them more expensive in the long run than HQI which should be replaced
once/3 years although some German hobbyists replace them at the rate
of once every 6 months. A word of advice about replacing high
intensity bulbs. Make sure your fixture can be raised. When putting
in new bulbs you will be increasing the intensity of the light and
the corals may react negatively. By raising the bulbs you decrease
the intensity and give the corals a chance to re-adapt. Over a
period of a few weeks you can slowly lower them again. Wilkens and
Birkholz (1986) recommend that HQI lights can also be shielded with
white translucent plastic to reduce their intensity when introducing
new animals or replacing new bulbs, until the animals have a chance
to readjust.

IV: Nutrition
The last topic I would like to address is coral nutrition. As
mentioned above, most corals contain symbiotic algae in their tissues
which can supply some of their nutritive needs. I say some because
the degree to which zooxanthellae contribute to a coral's nutrition
has been the subject of much research over the past 20 years. It
seems that the amount varies between species. In some forms over 90%
of a coral's nutrition can be met by the zooxanthellae while in
others this figure is much lower (60%). The general rule seems to be
the smaller the polyps, the more important the zooxanthellae are.
Corals feed in a variety of ways. The larger polyped forms can
actually feed on shrimp sized prey which they capture with their
tentacles. Other forms collect the slime that forms on the polyps
and swallow the microorganisms and detritus trapped in it. Still
others can directly absorb nutrients (ammonia, nitrate and phosphate
used by the zooxanthellae as well as various amino acids) from the
water. The problem comes when deciding when and how much to feed.
In my own personal opinion many coral species do not need direct
feeding. Many get more than enough from natural sources in the
tank. Every time you feed your fish nutrients are added to the
water. The presence of live rock and their associated algae and
bacteria produce copious amounts of nutrients, vitamins and other
products. Even in the presence of a highly efficient skimmer,
Wilkens (1987) found that the levels of amino acids in the aquarium
were many times higher than on the reef. Those polyps that are large
enough to be fed small pieces of shrimp can be fed once a week or two
by directly placing pieces of food on some of the polyps. The
zooxanthellae require phosphates and although they may be able to
absorb this from the water it is generally felt that the main source
is from the prey captured by the polyps. However, some forms of soft
coral (e.g. Xenia) have never been observed to feed. Lacking
stinging cells in their tentacles, they may absorb phosphate directly
from the water and may not be capable of prey capture. Be very
careful about overfeeding your coral i.e. feed SPARINGLY at least
until you get a feel for how much the coral can eat. An occassional
feeding of live baby brine shrimp or one of the better liquid foods,
may be appropriate for some specimens but not others. Pay careful
attention when feeding, if it looks like the coral is not ingesting
any food then perhaps it does not require additional feeding. Some
species of mushroom anemones will feed if food is placed on their
discs but others are never observed to feed. A general rule with
mushroom anemones is that if they have large bumps or tentacle-
shaped protrusions, you should try and feed them. Smooth surfaced
forms generally obtain enough nutrition from their zooxanthellae.
Coral health can be determined by how quickly they can repair damaged
tissue. A healthy coral can easily withstand small areas of damage
and should be able to keep fouling organisms from invading its tissue.

The Ethics of Keeping Corals
The keeping of live coral has many detractors who, for well
intentioned reasons, would prefer that keeping of live coral be
banned. Although this is a commendable stand it may be a little
short sighted. We need to understand as much as possible about these
animals and learning to keep them in closed systems would provide a
greater opportunity for study. If the greenhouse effect becomes fact
in the next 20 years we will see dramatic rises in the world's ocean
levels. If coral growth cannot keep-up then many thousands of square
kilometres of reef will disappear as it has done in the geologic
past. If we can learn to keep these animals and reproduce them in
closed systems we may be able to preserve some species. I know this
is a little pie-in-the- sky but this is my article so there! Very
few scientific labs are working on maintaining corals in closed
systems, just about everything known about keeping corals has come
from hobbyists! Finally, I do not agree that everyone should be
allowed to keep all types of corals. What I would like to see in the
future, are restrictions on not only th types of coral imported but
also their numbers. Perhaps only reputable wholesalers/retailers who
have a demonstrated expertise in keeping corals should be licensed to
sell them. They, inturn, should sell the coral only to those
hobbyists who have demonstrated the ability/knowledge necessary to
keep them. Many corals are very easy to keep and propagate through
cuttings, just like plants. Let us, as a society, concentrate our
efforts in this area so that our dependance on wild stocks can be
reduced. At least one retailer has begun to do just that! ORNAMENTAL
AQUATICS (416-627-1010) in Dundas, Ontario sells his own tank raised
clownfish, gorgonians, Xenia, Florida False Coral (Briareum sp.) and
Bubble Corals!

Summary
When the proper lighting is obtained you will find that your aquarium
and its inhabitants will look more vibrant and alive. However, this
can quickly change if appropriate water quality and nutritive
conditions are not maintained by the aquarist. This is a serious
hobby and if you are not prepared to devote the time and energy
necessary to maintain these systems then stay away from them.
Advertising copy that claimed that these systems were maintenance
free were highly misleading, however, once your system is running
properly it takes only weekly or monthly chores to keep it
functioning that way. The key lies in observation. Watch your tank
closely every day and look for the lightest changes. It may be
nothing or it may be the start of something bigger. Better to
identify it early so that you have more time to correct it before the
problem gets out of hand.

References
Burleson, J. 1987. Miniature reef aquarium lighting. Seascope 4
Fall:1-2.

Dustan, P. 1982. Depth-dependent photoadaptation by zooxanthellae of
the Reef Coral Monastrea annularis. Marine Biology 68:253-264.

Falkowski, P.G. and Z. Dubinsky 1981/ Light-shade adaptation of
Stylophora pistillata, a hermatypic coral from the Gulf of Eilat.
Nature 289:172-174.

Kinzie, R.A., P.L. Jokiel and R. York 1984. Effects of altered
spectral composition on coral zooxanthellae associations and on
zooxanthellae in vitro. Marine Biology 78:239-248.

Moe, M.A. 1989. The Marine Aquarium Reference: Systems and
Invertebrates. Green Turtle Publications, Plantation, FL.

Mohan, P.J. 1990. Ultraviolet light in the marine reef aquarium.
FAMA 13(1):4-6,156-160.

Sprung, J. 1988. Captive Reefs. Tropical Fish Hobbyist, October
1988:72:-84.

Sprung, J. 1989 Reef Notes. FAMA 12(11).

Thiel, A. 1988. The Marine Fish and Invert Aquarium. Aardvark Press,
Bridgeport, CN.

Wilkens, P. 1987. Niedere Tiere: Steinkorallen, Scheiben- und
Krustenanemonen. Engelbert Pfriem Verlag, Wuppertal.

Wilkens, P. and Birkholz, J. 1986. Niedere Tiere: Rohren- Niedere
Tiere: Rohren-, Leder-, und Hornkorallen. Engelbert Pfriem Verlag,
Wuppertal.