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Selecting lighting for a nano tank is a difficult topic since there are so many lighting fixtures to choose from and also different types of tank setups. To help someone try and make this decision, it would be helpful to know what one plans to keep in the tank.
If you are thinking of only keeping fish, or as it is known here, FOWLR--fish only with live rock--then lighting is not of major importance. If you plan on keeping a nano reef tank, i.e., your plans include adding corals, then lighting is of extreme importance.
We all know that there is the old frowned upon rule of thumb saying, one inch of fish per gallon. Well, there is a lighting one also. This is only a rough guide. Minimal lighting (low to moderate) is considered 3-5 watts per gallon. This should NOT be used as a major decision making factor. Why? Many things affect how light reaches your corals including (to name a few):
1) water depth
2) lumens
3) reflectors or mirrors
Many corals will exist under low to moderate lighting including soft corals, zoanthids and leathers. Many LPS (large polyp stony) corals will work too. However, if one wishes to keep many of the more challenging and colorful corals, SPS (small polyp stony) corals or tridachna clams, you will have much higher lighting requirements.
For most people, compact fluorescent lighting (PC) should do well. They generate minimal to moderate heat and there are many fixtures to chose from. Most fixtures come with built in fans to dissipate the heat created. With enough PC's, you can support most anything in your tank. Typically they are combined with 'actinic' or blue lights with a spectrum in the range of 10,000K. Actinic lighting is a blue colored light included for several reasons. Two reasons are:
1) blue actinics give a beautiful color to the tank and assist in making the corals fluoresce
2) some people feel that this blue color spectrum replicates the light wavelength that the zooxanthellae in corals 'see' at depth for use in photosynthesis (remember, reds, yellows and oranges are the first to be filtered out by water).
Many people don't bother with actinics if they have light frequencies in the 10K-20,000K range since this wavelength is part of that spectrum. Many aquarists will recommend metal halide lighting if you choose to go the SPS route or if your tank is deeper than 18-20 inches. Metal halides penetrate deeper water depths better.
Metal halides give that beautiful shimmering effect we see with sunlight in a swimming pool. Metal halides generate a lot of heat and must be cooled and elevated above the tank. Some generate enough heat to require chillers, cooling systems to keep the tank temperature down. Most do well simply with fans and keeping the light at a certain height above their tank. Disadvantages include the cost of running them and that they are MUCH more expensive than PC's. However, keep in mind the number of tubes added for PC's, fans, etc and the cost of a metal halide may equal out (as well as the decreased loss of corals with underlighting).
Other lighting include VHO, very high output fluorecents and HO, but, these are usually not used in nano tanks.
Other useful facts:
1) Typical photoperiod is 10-12 hours per day
2) PC's should be changed every 6-8 months as the spectrum diminishes/changes over time unnoticed by our eyes
3) Some people install actinic lighting (blue lighting) to come on first to simulate sunrise and go off last to simulate sunset
4) Highly recommended to use timers to prevent overlighting (good rec for professionals with long hours) or forgetting to put lights on
5) Moonlight LEDs are becoming very popular. Some even connect the moonlights to moon phase timers that simulate the lunar cycle. Some claim it assists certain fish with reproducing. Some of your corals may fluoresce under this lighting at night.
6) Some people save money by buying lighting components from a lighting store (DIY)
Summary
1) If you are going FOWLR, a single conventional striplight should do. You can upgrade later.
2) If you are planning a reef tank with easy low light requiring corals, compact fluorescent lighting should be fine
3) If you are planning a complex reef tank with SPS corals and clams, higher spectrum/wattage PC lighting is needed, or, better and for more experienced aquarists, metal halides.
If you are thinking of only keeping fish, or as it is known here, FOWLR--fish only with live rock--then lighting is not of major importance. If you plan on keeping a nano reef tank, i.e., your plans include adding corals, then lighting is of extreme importance.
We all know that there is the old frowned upon rule of thumb saying, one inch of fish per gallon. Well, there is a lighting one also. This is only a rough guide. Minimal lighting (low to moderate) is considered 3-5 watts per gallon. This should NOT be used as a major decision making factor. Why? Many things affect how light reaches your corals including (to name a few):
1) water depth
2) lumens
3) reflectors or mirrors
Many corals will exist under low to moderate lighting including soft corals, zoanthids and leathers. Many LPS (large polyp stony) corals will work too. However, if one wishes to keep many of the more challenging and colorful corals, SPS (small polyp stony) corals or tridachna clams, you will have much higher lighting requirements.
For most people, compact fluorescent lighting (PC) should do well. They generate minimal to moderate heat and there are many fixtures to chose from. Most fixtures come with built in fans to dissipate the heat created. With enough PC's, you can support most anything in your tank. Typically they are combined with 'actinic' or blue lights with a spectrum in the range of 10,000K. Actinic lighting is a blue colored light included for several reasons. Two reasons are:
1) blue actinics give a beautiful color to the tank and assist in making the corals fluoresce
2) some people feel that this blue color spectrum replicates the light wavelength that the zooxanthellae in corals 'see' at depth for use in photosynthesis (remember, reds, yellows and oranges are the first to be filtered out by water).
Many people don't bother with actinics if they have light frequencies in the 10K-20,000K range since this wavelength is part of that spectrum. Many aquarists will recommend metal halide lighting if you choose to go the SPS route or if your tank is deeper than 18-20 inches. Metal halides penetrate deeper water depths better.
Metal halides give that beautiful shimmering effect we see with sunlight in a swimming pool. Metal halides generate a lot of heat and must be cooled and elevated above the tank. Some generate enough heat to require chillers, cooling systems to keep the tank temperature down. Most do well simply with fans and keeping the light at a certain height above their tank. Disadvantages include the cost of running them and that they are MUCH more expensive than PC's. However, keep in mind the number of tubes added for PC's, fans, etc and the cost of a metal halide may equal out (as well as the decreased loss of corals with underlighting).
Other lighting include VHO, very high output fluorecents and HO, but, these are usually not used in nano tanks.
Other useful facts:
1) Typical photoperiod is 10-12 hours per day
2) PC's should be changed every 6-8 months as the spectrum diminishes/changes over time unnoticed by our eyes
3) Some people install actinic lighting (blue lighting) to come on first to simulate sunrise and go off last to simulate sunset
4) Highly recommended to use timers to prevent overlighting (good rec for professionals with long hours) or forgetting to put lights on
5) Moonlight LEDs are becoming very popular. Some even connect the moonlights to moon phase timers that simulate the lunar cycle. Some claim it assists certain fish with reproducing. Some of your corals may fluoresce under this lighting at night.
6) Some people save money by buying lighting components from a lighting store (DIY)
Summary
1) If you are going FOWLR, a single conventional striplight should do. You can upgrade later.
2) If you are planning a reef tank with easy low light requiring corals, compact fluorescent lighting should be fine
3) If you are planning a complex reef tank with SPS corals and clams, higher spectrum/wattage PC lighting is needed, or, better and for more experienced aquarists, metal halides.