Some people run 14K Hamiltons or Phoenix without supplimentation. If you do suppliment, you won't need much.
<a href=showthread.php?s=&postid=11371274#post11371274 target=_blank>Originally posted</a> by JediReefer
The blue spectrum of lighting is all aesthetic.
Not so. Actinic is mostly in the 420-460nm range and provides useable light.
Part of a thread by "waterkeeper:
Our eyes are most sensitive to light in the yellow-green region centered on 555 nm. When lumens were introduced as a measurement system it was decided to use this single wavelength as the benchmark. If you use a photographer's light meter the meter is "weighted" to favor this region of light.
This is all well and good in the area of photography but not so hot when it comes to keeping things alive in a reef tank. Photosynthetic life is important in a healthy reef. Be it coralline on the live rock or zooxanthellae harbored in the coral they need light to survive. Unfortunately, light at 555 nm is not it.
Well, the entire visible spectrum plays a role in photosynthesis, it is just 555 nm is not exactly the wavelength that most algae would choose if put to a vote. If I plan to take a picture then using a regular light meter is fine. If I plan on illuminating a reef tank it tends to fall short.
One of the first lights to make headway into the world of reefing was the actinic fluorescent. Actinism is the term for light that induces chemical reactions. It just so happens that light in the region of 420-450 nm is very important to photosynthesis, a chemical reaction. Actinic lights produce much of their light at this wavelength. Actinic lighting may have been somewhat of a novelty turned important. When it first came out around the late 70's it was mainly touted as great tank lighting because in highlighted the fish. The LFS loved it and many of their SW tanks had it. If you can see a tank with just actinic lighting in use you'll see what I mean. Under actinic the water appears more transparent and fish and coral tend to stand out. Some corals even fluoresce under these lamps.
It was only after they were in use for awhile that the other benefits to a reef tank became apparent. An actinic lamp has a terrible CRI (about as bad as you can get ) but in a reef tank it adds an abundance of useable photosynthetic radiation. That, and with its ability to highlight the critters inside the tank, made it all the rage. Suddenly corals that have never been able to survive in a tank where not only surviving but growing. Actinic lighting is one of the great advancements in reef husbandry.
http://archive.reefcentral.com/forums/showthread.php?s=&threadid=550860&highlight=actinic+useable+light+spectrum