I certainly do not have all the answers here either, but I do know what has worked for me for many years, ever since I first saw metal halide lights, in Germany, over Reef aquariums in Pet shops and at Hobbyist's homes, over their reef aquariums.
Their tanks looked so much better than what I was accustomed to see that, when I represented a German company in this country, I was most enthused about bringing that type of lighting into the market place in the United States and Canada. I experimented with these metal halides (Osram Power Stars at that time), and had the same type of success over my own aquariums as the tanks that I had seen overseas, in Germany, France and England.
Soon thereafter, a foresighted American manufacturer, Omer Dersom of Energy Savers Unlimited, took a large commercial risk, and decided to offer metal halide lighting to the Hobbyist at much more affordable prices than what they had been available for up to then. First he introduced 4300 K degree bulbs, and recently 5500 K degree Daylight (blue-white) ones. His strategy obviously worked, and such metal halides are now the norm of every discriminating Hobbyist I know.
Still, some resellers in this country advocate a different form of lighting, and put much too great an importance, I feel, on the use of actinic lights, often, if not always, mixed with other fluorescent tubes. To me, there is no question at all, that time will prove me right. Metal halide lighting is the only safe way to go, and where you should put your money if you are in the market for lighting for a Reef tank.
Do not misunderstand me, even though you can keep quite nice reef aquariums with certain types of fluorescent lights, providing you use enough of them; the difference between such tanks, and similar tanks run with metal halide lights, is like day and night. If fluorescent tubes is what you use now, see later in this chapter for suggestions on how to improve your existing set up, by either changing the bulbs, or increasing respectively their numbers and/or output.
That metal halide lighting is the only way to go, is quite a strong statement, but one that I believe to be absolutely correct. My own experience, and that of many hobbyists I know, is plenty of evidence to support that statement. Tanks lighted with metal halides, especially the daylight types (5500K), just do a great deal better than other tanks I have seen. You can find evidence of that in my new series of videotapes dealing with "The Reef Aquarium Corals and Inverts: Types and Care" Parts 1 to 3, available from Aardvark Press.
Aquariums lighted with fluorescent tubes, just do not allow the corals and invertebrates to develop the way they do in tanks lighted with metal halides, and high Kelvin degree mercury vapors (clear types). The tanks may look nice, and some hard corals and some mushroom corals may show vivid colors, but at the sacrifice of their physical size and appearance. To me, at least, that is not an acceptable trade-off.
The only caveat when using metal halide lighting, is that you must use the right kind of metal halide bulb. If you do not, you will not get the results that I can otherwise guarantee you. The halides must be of the "high intensity discharge" type, meaning you will need a transformer box with them.
Don't be afraid though, when you buy such a lighting set-up you obtain all the parts needed in one purchase. You will not have to go out and buy any other parts separately. Keep this remark in mind, indeed, if you are offered a so-called metal halide that does not require a ballast (transformer) and that you plug directly into the wall outlet, you are being offered the wrong light ! Those are mostly Tungsten halogen quartz lights, which give off a lot of light, but also very yellow
light, not suitable for the reef tank.
Metal Halide Lighting and Corals :
Ever since I wrote "The Marine Fish and Invert Reef Aquarium" book, hundreds and hundreds of Hobbyists have called to ask questions about lighting, and also why I am so adamant about using metal halide bulbs. The reason is very simple: because they allow me to keep a Reef tank with invertebrates that open to the fullest I have ever seen, and keep them that way for the longest of times, not just a few days or weeks. Anyone who has seen my main show tanks can attest to that.
Visualize purple mushrooms (_Actinodiscus_ sp. and _Actinodiscus sharonii_) that are about 1/4 inch when they are closed, open to about 3 1/2 to 4 inches when fully open under metal halide 5500 K Coralife* bulbs.
Visualize the same purple _Actinodiscus_ species mushrooms lift off the rocks on which they are, so you can see a stem underneath them of about 3/8 to 1/2 an inch in diameter, and well over an inch long. I have never seen that happen in a tank with fluorescent tubes to a degree that frequent as it happens in aquariums with MH 5500K bulbs. The size coloring, and shape of _Actinodiscus sharonii_ is only one example of what can be achieved with such bulbs over a Reef aquarium.
Another good example of what metal halides can do for corals, is the coral _Catalaphyllia jardinei_, sometimes referred to as plicata as well (common names Elegance, or Elegant). Although they may stretch to quite a large size under strong fluorescent lighting, you will see them "grow" to about 1.5 to 2 times that size under metal halide lighting, combined, of course, with good water quality (redox of 300 mv or more in the aquarium itself). Some specimens in my tank are literally huge, especially considering that the hard part underneath in only about 5 inches long and 3/4 of an inch wide, and is not branched.
Elephant ear corals, _Discosoma_ types, which normally stay flat and close to the rock to which they are attached, open up wide, stretch and curl at the edges, even when they are not feeding, and become larger than you have ever seen them under fluorscent lighting, even when supplemented with special blue and green bulbs. Elephant ear corals are delicate corals, feeding on both live foods and extracting nutrients from the water and from photosynthesis.
Many anemones, e.g. Clownfish anemones, of the "ritteri" type, migrate upwards closer to the metal halide lights, proof, obviously, that they find it beneficial. Additionally, the ones we have in the home show tank, do not lose their colors. I keep 2 large ones, and both are a good 15 inches across when they open up completely a few hours after the lights have been on. The noteworthy fact , of course, is that they were only about half that size when I originally placed them in that tank.
_Euphyllia ancora_, the coral with the kidney shaped end of tentacles (as opposed to the Tee-shaped end of hammer head corals, _Euphyllia cristata_), stretches its tentacles to a length of possibly as much as 6 inches. In the same tank _Euphyllia glabrescens_, the coral with the whitish round ended tentacles increases in shape to be point where it bulges out of the hard skeleton.
I could go on and on, but I am sure that you have gotten the point I am trying to make. Although other forms of lighting may be adequate, metal halides, of the high intensity discharge type, 5500 K, give better results in Reef Tanks.
It has also been said that metal halides "burn" corals! That erroneous rumor is now heard many times in discussions about light between Hobbyists ! Be aware that some companies that we think were responsible for that statement, now sell metal halides imported from another country, whereas before they were touting, over and over again, the benefits of actinic light.
Metal halide lights, used properly, with UV shields, if so recommended, do not harm corals. Not a bit. The sun gives off much more UV than even the strongest metal halides can, and beats on the coral reef day in, and day out, granted with the water as a partial shield.
Actinic light can, under certain circumstances be beneficial, especially if the other lights used in conjunction with it, are not of as full a spectrum as they should. In this respect be aware that Osram bulbs, as now sold in this country, have a spectrum of only 4300 K, not nearly as good, for our purpose, as the newer 5500 K metal halides. 4300 Kelvin degrees is very good, but 5500 K is much better. The experiences of others who have used them, and my own, are proof of that.
Actinic light will, often, give the tank an eerie look, especially if you use several strong ones. This distorts the appearance of colors, and makes animals look unnatural. Metal halides, because they are a much more "complete" light source, do not. In fact, the 5500 K proprietary Coralife bulb, is rated as a daylight bulb, meaning that you will perceive the colors of the animals in your tank as "true" colors. On paper that may sound unimportant, but in reality, looking at an aquarium that does not look "real" is very strange for anyone visiting your house.
The photograph on the cover of this book was taken around 3:00 pm, while 700 watt of metal halide lights of the 5500 K type were burning for several hours. Those purple mushrooms look a lot better, I feel, than some others I have seen in photographs.
How much light intensity should you install? A lot if you can. The minimum I recommend is 2.5 watt per gallon of water in your tank. More if you want better results. Over a 55 gallon tank you can easily place 175 watts or more of metal halide lighting. I have 700 watts over a 135 in my house, and all are 5500 K metal halide bulbs.
Availability of lights, and their respective wattage, may make it necessary for you to adjust somewhat upward or somewhatdownwards, but use 2.5 to 5 watt per gallon as a guideline.
You can, nowadays, buy metal halides mounted in hoods(Coralife-Energy Savers), or as pendants (Thiel-Aqua-Tech ). Which one ofthese types to prefer is a totally personal choice.
Both types are equally effective at providing the rightlight for your corals and invertebrates. Hoods are closer to thewater, and may thus be more efficient than pendants; pendants on theother hand leave the top of the tank open, and appear more attractive tosome. There are many similar trivial differences of that typebetween both and, as a result, there are proponents and opponents of bothtypes. Fortunately both types are available for sale in both the UnitedStates and Canada, and so the choice is yours.
If the light intensity you require, or plan to use, is lower than 175 watt, no 5500 K bulbs are available at this time. You can of course still use such a bulb, but in pendant form. This will allow you to place it a distance from the water, thus reducing the intensity, and spreading the light out better over the entire aquarium. Alternatively you should use 4300 K bulbs, which are available in 100 and 175 watts versions.
Contrary to popular belief, based on some articles that appeared in hobby magazines, metal halide light gives off a lot of "blue" light as well, especially the newer 5500 Kelvin degree Coralife bulbs. Cost is always a factor, unfortunately. Metal halide lights can be expensive, especially if you need several of them. Buying pendants can be a significant expense, albeit a good one.
Fortunately, Energy Savers Coralife came to the rescuesome time ago by offering, what they refer to as, The Light Spot, a sort of do-it-yourself metal halide lighting set-up, greatly reducing the cost of installing metal halides over your aquarium. For more information call them direct, they advertise in all hobby magazines. We tried one, and can attest to the fact that their installation is really verysimple, and the price is right too...
Fluorescent Lighting
Many Hobbyists now use fluorescent tubes over their tanks. At Thiel-Aqua-Tech we have used both metal halide lighting and fluorescent tubes too. We have, as you may have surmized, found that over reef aquariums metal halide lights give much better results, and have switched to using only the latter type. We also described the results earlier.
If you are now using fluorescent tubes, or are considering doing so, our recommendations are as follows :
Because it often is difficult, if not impossible, to get enough regular fluorescent tubes (400mA) over the aquarium to match the minimum of 2.5 watt per gallon recommended, one solution that many Hobbyists resort to, is to use high output (800mA) fluorescent tubes. Such bulbs give more intensity per watt, and can be a viable solution, albeit not necessarily a less expensive one than using metal halides.
Check with Energy Savers, as that company offers a wide variety of hoods, in many configurations, and may be able to come up with a workable solution for you. You could, for example, get the hood from them, and acquire bulbs elsewhere, if that is the way you decide to go.
Besides regular and high output fluorescent tubes, some specialty lights are available as well. Usually these lights are of the daylight or higher spectrum, and are worth considering too. We do not recommend very high output (1200m A) tubes, because they lose their spectrum very quickly, and would need replacing every 3 months or so, making their use a very expensive way to go.
Because new types of lighting appear on the market all the time, watching for new developments in this area is certainly something a Reef Hobbyist should do. As techniques evolve, and progress is made, one can be sure that leading lighting companies such as Energy Savers, for example, will bring you what is state-of-the-art as time goes on. Progress is what makes this hobby exciting, challenging and moving forward to bring us even better reef aquariums.
At this stage of affairs in the Reef hobby, the best that is available, in my experience, are the daylight metal halides made by Coralife. I highly recommend them, and use them myself with great success. Their price is also less than a third of the 4300 K Osram bulbs advocated by some German circles.
[Albert J. Thiel requests that you make a $5.00 donation to the New Mexico School for the Visually Handicapped Children, 1900 North White Sands, Alamagordo, New Mexico 88310 (or other charitable group) if you download the entire book. This would be in lieu of the standard purchase price for this publication.]