Reef Tank Lighting

Reef Tank lighting is one of the most important aspects of reef keeping and undoubtedly the most discussed debated and disagreed about too!
Proper lighting intensity is essential for the corals to carry out the process of photosynthesis, the process through which they create energy needed to survive and grow. Whatever the approach or equipment be, the ultimate goal of al lighting methods is to provide photoperiod, intensity and proper spectrum for your reef inhabitants to flourish and thrive easily.
The commonly used phrase, "watts per gallon," is a way of expressing the lighting necessary for a tank by the ratio of the power used to illuminate the tank divided by the tank size in gallons. Many hobbyists suggest that an adequate amount of light would vary between four watts and six watts per gallon for low light coral and as much as ten watts per gallon (or more) for light loving coral. While such a rule of thumb may initially sound like a good idea, it should only be used as a rough guideline and not as a strict rule. Obviously, such a loose rule is misleading, and aquarists need to consider more than just "watts per gallon." Specifically, they must take into account the height and overall size of the tank.
Lighting in the reef aquarist parlance is generally expresses in “Watts per gallon”. A thumb rule suggested by many says that light should vary between four to six watts per gallon low light coral and about 10 watts for corals with high light intensity needs. But this is not a hardcore researched rule and should only be used as a rough estimate. There are other factors like the overall height and depth of the tank before making a choice.
A very innovative method of using a multi-light system with timers or controllers to vary the number of lights on at any given time is probably the most effective one. In this system usually one bulb remains on for an hour, then all the bulbs for 10 hours and then just one is left on for next hour. This method actually simulates the sun passing over. This is as close one can get to re create the natural lighting mechanism of the sun.
There is no doubt that steady advances made in the light manufacturing industry have made these equipments better and better and more efficient.
The solution for your reef tank can vary in price from inexpensive to very expensive. What suits you depends upon the kind of life you want in your tank.
Two primary lighting equipments available in the market and widely used are Fluorescents and Metal Halides (MH).
There are several variants of Fluorescents. These are the least expensive or rather value for money choice and are suitable for practically all light choices. These are relatively cool (literally speaking, not metaphorically!). And generally they last for many months before requiring replacement. Examples of different fluorescents are: Normal Output (NO), High Output (HO), very High Output (VHO), Power Compacts (PC) and T5’s.
Among all the variants in fluorescents you can call Power Compacts a next generation fluorescent bulb. They have a modern twin tube design, basically a fluorescent tube that is bent in half. Therefore much greater light intensity is produced than other standard fluorescent variants. The fluorescent tubes are available from 10 to 130 watts and can last up to a year to two.
You should opt for a fluorescent if your reef tank is not very deep. There are some corals like SPS corals for which the light intensity of fluorescent is not enough. So keep these points in mind while thinking of a fluorescent.
The other popular option is the Metal Halides. There are different parameters to be considered here too. They are the most intense of all available lighting systems. If you have a tank which is deeper than 20 inches, this is what you may consider to buy, as halides have greater capacity to penetrate to depths beyond 20 inches. Apart from the utility they beautify your tank also by producing sparkling glitter lines.
So if you want to have a successful reef, know your tank and corals well and then make an informed choice. Only then ‘Let there be Light’!