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Your crash course on lighting.
Lighting is one of the many keys to creating a successful reef. Corals get their food from light by photosynthesis. If there is not enough light to stimulate the zooxanthellae (photosynthetic cells) the corals will surely perish. John Tullock makes an analogy between the accelerator pedal (light intensity) and the speed of your cars engine (photosynthesis). If you press down on the pedal (increase light intensity) the engine revs up (rate of photosynthesis increases). There are many ways to calculate exactly how much light is needed over a reef-tank, but the simplest way is to shoot for a bare minimum of four to 6 watts per gallon. My tests have shown no adverse Effects on corals with 10.75 watts per gallon over the tank. Every bulb also has what is known as a Kelvin rating. The best way to describe the Kelvin system, would be to make relation between the spectral output of the lamp and the spectral output from the sun. The higher the Kelvin rating, the closer the lamps output to natural sunlight. Your bulbs should have at least a 5000 Kelvin rating. With fluorescent lighting this is generally not a problem. There ratings are generally above 5000. Metal halides on the other hand, can range anywhere from 3000 K to 20000 K.
Power Compact Lighting Explained
PC lighting is a great choice for smaller tanks. Especially mini or micro reefs. They come in various wattages just like fluorescent lighting does. The tubes are smaller, put out less heat, last longer, and put out the same amount of light. These really are becomming the way to go. Alot of the same principles apply to PC's as normal fluorescent tubes. So rather than duplicate myself, please read-on.
Fluorescent Lighting Explained
Fluorescent lighting has its good points and its bad points. Fluorescent lighting has a cheap setup cost, but in comparison, it also has a high maintenance cost. Fluorescents are good for tanks that are less than 1 1/2 feet deep. However, one thing to consider is, not to have corals that need intense light at the bottom of the tank. I.E. The Tridacna sp. clams. These guys wont fair too well under fluorescents. Before I start getting flamed, I do know of people that have accomplished this, but it is not something I would recommend. There are two tube types when it comes to fluorescence, Actinic and Daylight. Actinics have a very blue glow about them, allot like a black light. The daylight tubes are just that, White in nature. The fluorescent tubes that I would recommend are the Coralife Magtinic ( for the actinic ) and the Coralife Trichromatic ( for the daylight ). In retrospect, I also see no problems with using all Coralife 50/50's ( each bulb is half actinic and half daylight.). I have seen this done successfully in other tanks.With excellent results I might add. fluorescent bulbs run much cooler when compared to Metal Halide lighting ( discussed later ).
However, their output is not the greatest in the world.There are a few different types of output wattage's. NO. Normal Output. these normally range in the 20,30,40 watt range. Then there is HO. High output. These normally range in the 60,70,80 watt range. Then there is VHO. Very High Output. These guys normally range in the 90,100,110 watt range. If you have the money to spend on the VHO's, I would strongly recommend it. As the offer more intense lighting, while still keeping the heat transfer low. They must be changed every six months or their spectrum begins to shift. Once the spectrum shifts, you can expect to have unwanted algae growth problems. In my opinion, fluorescents. should really only be used on smaller tanks. 30 longs and below. The reason I say 30 L is because of actually how short this tank is in height. ( the shallower the tank, the better off you will be) Well, now that I have run Fluorescent lighting into the ground, lets move to metal halide, shall we? :)
Metal Halide Lighting explained.
Metal halides are in my opinion, the better way to go when lighting a reef tank. They start at wattage's. of 100W and can go to wattage's of 1000W or better. You only have to change the bulbs about once a year to every year and a half. It is also much easier to get higher amounts of light to the bottom of the tank where it is so desperately needed. They also have Kelvin ratings. Ranging from 3000 Kelvin to 20,000 Kelvin. If you use the 20,000K bulbs, you will not need Actinics to supplement the blue spectrum needed to heighten photosynthesis. They do however have some drawbacks. The start up cost for a singe 175W unit is about 200 clams. Pardon the pun. :) They also produce allot of heat, which is the last thing we need with all the powerheads and pumps and such that we have running in there already. They are also somewhat bulky and not so easy to manipulate. Once in place, they are a very stable source of light. The also give glitter lines, which adds a nice appearance to the tank.
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