Lights 101

[Rock]

What are the different light options out there and what are the pro's and cons. Is it just about watts? What does the 10000 k rating mean and how does that affect your system? I need all the education i can get.

[Jamie]

There's a lot of information out on the web and many many different opinions. Basically you have 4 viable options for lighting:

Fluorescent Lighting:
Power Compacts (PC), T12 Very High Out-put (VHO), and T5 HO/VHO. Each of these options in lighting are tubes that are filled with some sort of powder that reacts when energized and emits light. The terms T12 or T5 refer to the diameter/size of the tube...12 being larger than 5. In the past, most common household bulbs were T12..but the newer, more efficient/skinnier bulbs are becoming more available. T5's are the newer technology of the above mentioned and in my opinion are the best of these three. They work best with high quality individual reflectors. With good bulbs and reflectors you are able to keep most all corals/clams/etc. with no problems.

Pros: Less heat emitted, cheaper bulb replacement, more options in lighting color
Cons: Not as powerful as metal halides, requires more bulbs

Metal Halide (MH) Lighting:
These are really a step above all of the fluorescent options as they can provide a concentrated beam and can penetrate deep into the tank better. They put off more heat as a result. Most people battle the excess heat with a chiller or an open top with fans. If you use fans, be prepared for a lot of evaporation. Generally you need 1 MH bulb for each 2 ft of tank length.

Pros: Most intense light available
Cons: Hot, Bulbs tend to be expensive, Limited on bulb color selection (for best coral coloration, most people supplement MH lighting with VHO actinics to make up for the light spectrum that the MH bulbs don't adequately include)

Measuring the efficiency of your lights by how many Watts they put out are a thing of the past. It is all about quality. Within quality, there are many factors to consider...but most importantly Photosynthetically Active Radiation (PAR). In very simplified terms, this is the usable light that the corals need to grow. The higher the PAR, the better off your corals will be. There are other things to look at like lux/lumens and color rendering index etc...but I really pay attention to the PAR.

MH's generally have the highest PAR available in any bulb....though T5's aren't that far behind if you have a quality set-up.

As far as Kelvin goes...it refers to the color temperature that the bulb is burning at. Most household bulbs have a very low Kelvin....3000-6000. Good plant growth occurrs in the 6500ish range. Corals however utilize anywhere from 6K to 10K to 20K. The deeper the corals are in the water, the more of the yellow and red spectrum of light is filtered out...leaving mostly blue (20K range). Generally speaking though...as far as corals are concerned, 10K is considered more of a "growth" bulb and 20K is more of a blue/bring out the colors of the coral type of bulb.

This is all very general information and I am in no way an expert...so take it for what it's worth.

[Fish4life]

I'd say you did a pretty good job of sum it all up. With t5's it really depends on the reflectors and bulbs. the best bulbs on the market right now are ATI bulbs. The best reflectors are Icecap Slr's. Each of the ATI bulbs produces about 300 par. I am not sure what a MH bulb produces.

[Rock]

very nice. Simple straight to the point. Thank you for taking the time.

[Texreefer]

Good Job Jamie

[Jamie]

Thanks, Glad to help.

[marshall.read]

very well done jamie