Lighting 101

I'll put in my 2 cents and hopefully others can point out where my opinion was incorrectly stated as fact.

PC or CF (compact fluorescent) is not low light. It should be considered med-high light for it can also grow sps(small polyp stony) coral, the most light demanding coral!

Unfortunately the general public has this notion that wattage equals intensity. Watts are the measure of how many volts and amps are used by the light, in other words, power consumption!

What we might do is classify these lights by their lumens, in other words how much light energy is emitted! In addition we need to be thinking of the appearance of the light to the actual organism. If I remember correctly this has been called PAR (Photsynthetic Activated Response or something like that). PAR also considers the light spectrum as well. Coral do best with a certain spectrum of light depending on where they naturally grow in the watery depths.

MH can provide the highest lumens from a single point of light which most closely resembles the sun. This seems to be what sps and clams do best with because they come from the shallow depths where the sun is visible as a point of light.

VHO (Very High Output Fluorescent) and the newer CF/PC (Power Compact Fluorescent), in sufficient quantity, can provide the same lumens as MH but the emmitted light is spread over the entire surface of the tubes. This changes the way the light looks to a coral. As light travels through the ocean water it diffuses. This effect is how coral perceive fluorescent light, as though they are 10 feet or deeper receiving diffused light. Most coral are in this deeper category, BTW.

The ballasts for all lights are hot and are best kept out where the heat can dissipate away from the tank water. Most people place the ballast outside the stand either on the back or sometimes on top of or on the back of the hood. The MH lamp itself aside from providing a single bright point of light also emits a lot of heat. That's why MH lighting always includes fans to cool the inside of the hood. Hoods are even optional with some MH setups.

Well I've said enough. Here are 4000 more words that an avid hobbyist will (or should) understand.





These are courtesy of a Jacques Cousteau book, I can't remember it's name.

Edited by Mark Peterson

I forgot to write about Kelvin temps or spectrums of bulbs.  The higher the Kelvin rating, the bluer the bulb.  Coral that grows close to the surface, like sps, like yellower bulbs, like 6500K or 10000K bulbs, because the sun light is still yellow at the surface, as Mark's pictures show.  BTW, those are great picures Mark.  Every LFS should have them on a poster to show customers what different temps of light do.  Thank goodness dive gear has improved since those pictures were taken.

Jon, is the T-5 that you mention above the European HO bulb?  I thought that the common T-5 around here were only 36 watts for a 48" bulb.  I didn't think that the European T-5's had made it over here yet.

Yup, the high output.  You can buy then on line at a few places.  Aquatica sells T5 bulbs too, but I don't know if they are high output or not.  The actinic I saw at Aquatica looked like the "blue" PC bulbs.  Didn't look as good as vho actinics at least to my eyes.  I came across a place on line that sells both "blue" and what they call "true actinic" T5 bulbs, so there must be both floating around.

The Home Depot here in town uses T5 bulbs rather then HID lights for the whole store.  They're very bright and it looks like they fit about 8 bulbs in a fixture that normally would only fit 4 T12s.

interesting thread on RC about T5s ...  http://reefcentral.com/forums/showthread.php?s=&threadid =239653

T5s sound like a nice alternative to PC or VHO to me... more lumens for your wattage dollar.  plus, those tek-light hoods are pretty slick looking.

if you were going with T5s over a standard 55g 48” tank you could fit 4x54W (total 216W) T5s (48"x11"x2.5”) for the SLS Tek-Light. which would put you at 17496 lumens. compared to something like a 4x110W (total 440W) VHO hood (49"x13"x5") at 19800 lumens. you might even be able to squeeze a 6x54W (total 324W) T5 hood (48"x15"x2.5”) over a standard 48” 55g tank which would put you at 26244 lumens.

please correct me if I’m off-base about anything here… I’m still learning and this is also a question.

Does anyone know how the Halogen lamps compare to metal halide?  I am not familiar enough with MH or Halogen to know what the wavelengths of each are.  Does MH produce light in all wavelengths like the sun or is it more specific?

Halogen are too intense in the "UV2" wavelength which will burn quickly. Not recommended without a filter, plus they are so yellow, most people don't like the color.

when I inquired at aquatica they said they had two versions, one a german one (lots of $$$$) and the other was a 20 or 25 watt chinese version.  Would take a lot of those little 20's to get enough light, and they are one piece--so you can't really mount a reflector behind them.  I have mh and actinic pc's.  Seems to work good for me.

Peregrinus, those are so expensive!!  I friend of mine had an Acura Legend and put HID headlights in it for about $800.  I would assume that those would be very expensive to get for tanks.  But maybe someone will figure it out for cheap.

This tank http://www.utahreefs.com/heil.html was lit with 2 150 watt halogen and 2 40 actinic fluorescents. The gallery is outdated, since these pics are several years old. Anyway, Mark is right - the halogens are very yellow. I ran them without any type of filter. I called GE once and they indicated the color temp was around 3500 Kelvin. Not ideal - but I was able to keep soft corals and even a LT anemone. (that is still very happy in my new tank).