Lights are one of those areas that are going to be debatable for at least the next millennium  You could go through hundreds of different opinions and get many different answers as to what is "Best".  What it really boils down to is this.  What you want to keep and how much money do you have.  If you find out that you want to keep things that require more light than you have money for you have only two choices.  Change what you want to keep or wait until you have more money!  There really is no other way around this.  If you buy crap lighting hardware you will be in essence building a money pit.  By the same logic if you overspend on lighting that will not be utilized by the things you are going to keep, you have just wasted a lot of money.  

    Some people are of the opinion that only a Metal Halide (MH) lighting setup should be used on any reef tank.  Others are sure they can get by with only regular (RO, not to be confused with reverse osmosis) or high output (HO) fluorescent lighting.  Yet others swear that Power Compact is the way to go or that you need at least Very High Output (VHO).  My opinion is that in all cases they are both all correct and all dead wrong.

    Before you become even more confused I suggest you go back and re-read the first part of this lighting section.  I hope that you notice that the key is in fact two parts.  Money and Need!  Nothing more and nothing less.  If you simply have no clue what you want to keep, your dead in the water trying to make a lighting decision.  Same thing if what you want to keep needs more light than your budgeted for.

    Now as for you blockheads out there that are sure one form of lighting is far superior to any other no matter what the application.  All I have to say to you is prove it or hush!  Good, now that your quiet others can learn some of the basics of proper lighting.  Which is not to say that this information is all inclusive, but should give you some idea what your aiming for.  The idea is to give you the basic ideas that seem to slip the mind of many.  This should let you choose what is best for you without saying x is better than y or z.

    The first thing I want to point out is that the well entrenched idea of "You need X watts per gallon" is hopelessly flawed.  While true that it *could* get you close to what you need it is generally a worthless specification without more details.  Something similar would be like asking "How many pounds of trash can you get in garbage bag X?".  On the surface that question seems reasonable.  However, I am quite sure you can see the point that it would depend on the specific bag as well as what item you are placing in it.  Broken up glass wouldn't do near as well as goose down for example.  "Will that be paper or plastic?" would be another question. 

    Before you give up on the watts per gallon concept completely I would like to point out a couple of things.  There are generally accepted guidelines (given in watts per gallon) that use tank depth/dimension, type of lighting, and organisms kept that will get you to at least a good starting point with regard to lighting.  The catch is that many do not grasp that if you leave one of those out of the equation and still say "x watts per gallon" then the specification is all but worthless.  Another is that some form of life can be kept at just about any lighting level.  One of the tricks is to figure out which ones will do well in the amount of lighting you have or are planning.

    On a similar track, one thing to understand is that the more light the smaller the margin of error one has in regards to allowing nutrient buildup in the tank.  Meaning, all else being equal, if you accidentally overload a tank with nutrients that tanks negative response (usually one or more forms of bad algae growing like a weed) will be faster in the tank that has the higher light.  That is not to say high light tanks are a bad thing, just more detail demanding in my opinion.

    Next up would come things like PAR, CRI, and Lux among others.  Spectrum plays a very important role in reef aquarium lighting, it also is one thing that many cannot agree on.  Which looks the best and still does the job?  Personal taste has a role as well, so if you like more blue, less white or yellow than someone else that is just fine provided you are meeting the needs of your livestock.  Since many mounds of information exists on these things already I will not waste time outlining them yet one more time.  I will instead suggest you use them as keywords for search engines on the web.  You should come up with many results. You may also want to investigate the inverse square law as it applies to reef aquariums.  Distance and duration play a rather strong roll in meeting the overall lighting requirements of a tank.

    You Must change your bulbs ot regular intervals as suggested by the known properties of the bulb.  Generally the following schedule is a good starting place but is not absolute.
NO (Normal Output)- Every 6 months, some as soon as 4 months.  The one exception that I am aware of is the "Triton" light which will need replaced when it turns off.
HO and VHO (High output and Very High Output) - Same as NO above.  Many take their VHO's well past this and hearing about those that go as long as 12-18 months or more are not uncommon.
PC/CF (Power Compact/Compact Fluorescent) -  These go somewhere between 10 to 14 months, some cheap imports may start going at about 8 months or so.  If you have any of these keep an eye on them.  Some rumors ar around that the cheapest of these start to go or are gone by 4 months.
MH (Metal Halide) - Many say either 1 year or when it turns off, some others will say 10 to 14 months.  My opinion is that it seems to depend on both the wattage as well as the manufacturer of not only the bulb, but the ballast ass well. Search the net for information regarding the best time to change for whichever brands you may be considering.
The Earths Sun -  Never... at least we all hope so.  If it ever needs replacing your reef tank will be the least of your worries.  If your interested in my experience using the earths sun for aquarium light read my section on "Natural Light" found on the General Page.