Lighting

[Christian]

How I'd I figure out the watage of lights? I have a 54W t-5ho light wil a 54w 16,000k light with a antic light. So does that mean that it's 54w? But why do corals need from 10,000k and up light?

[Timfish]

How I'd I figure out the watage of lights?

Go by the wattage stated on the bulb. The "Fxx" number indicates the wattage. The "Txx" number indicates the bulb diameter in eigths of an inch. Many bulbs then have a number designating the color temperature. The lumens (or lux or PAR) will vary depending on manufacturer, bulb type, color temperature (K number) and age of the bulb. Lighting is a very complex subject and how corals respond to different intensities and spectrum complicates it further. For your best success I would urge you to match corals and lights to each other. Checkout some of the links here on ARC and Advanced Aquarist Online.

[Timfish]

But why do corals need from 10,000k and up light?

Corals most definitely do not need 10,000K and up light. Check this article on Advanced Aquarist:

http://www.advanceda...searchterm=None

Also DickPerrin with Tropicorium Corals who has been raising corals for more than 25 years uses 6500K bulbs. (Coral, June/July 2005 pg 10)

This being said I think a tank looks "whiter" with the higher K bulbs and appearance is important. Most of the flourescing pigments in corals use different wavelengths in the blue with a few using some from the green spectrum which adds additional emphasis on actinic or high kelvin bulbs along with the argument for photosynthesis. But a lot of pigments are not flourescing and if you want to empasize these colors you need to provide the required spectrum. An example from one of my aquariums is Pink Birds Nest. Under 12,000K MH they're nicely pink, under 20,000K MH they're brown with pink highlighting and under 6500K T5 they're pretty washed out (they are growing but I'm not impressed).

Edited April 2, 2010 by Timfish

[Bill B]

Very well put Timfish.

I am a printer and there are similar types of disparities in paper. A 110 pound stock may be thinner/lighter than a 67# stock because they are measured by a different standard. So Tim, yes 54 W T 5's are 54 watts. This is not necessarily a measure of penetrating power into the water. Actually once you get over 10 or 12k the penetrating power decreases even with the same wattage. Just in case you are not totally confused depending on the type of ballast and bulb (particularly in MH's) it may take quite a few extra watts to actually make the bulb emit it's labeled amount of light or you can overdrive them........

Bill

[+o0zarkawater]

Very well put Timfish.

I am a printer and there are similar types of disparities in paper. A 110 pound stock may be thinner/lighter than a 67# stock because they are measured by a different standard. So Tim, yes 54 W T 5's are 54 watts. This is not necessarily a measure of penetrating power into the water. Actually once you get over 10 or 12k the penetrating power decreases even with the same wattage. Just in case you are not totally confused depending on the type of ballast and bulb (particularly in MH's) it may take quite a few extra watts to actually make the bulb emit it's labeled amount of light or you can overdrive them........

Bill

Well the stock thickness is easy, you just have to explain to joe blow the way paper 'weight' is determined by parent sheet size, and then they will totally understand why a 67#VB is around the same thickness as a 110# index, and both feel thinner than a 65# Cover. Oh, and the 80# cover is similar to the 100# color copy coated cover. I don't even bother anymore. <end print talk>

(sorry I have no input for the light question)

[DaJMasta]

The color temperature (K) does relate to growth, but for basic aquarist purposes it's all about the way it looks. The higher the color temperature, the more blues will show through in your white light, the lower the color temperature the more reds. That's how they can get away with 'warm' and 'cool' white, where the warmer ones are lower kelvin rating and are closer to yellowish in color because of the extra reds in the spectrum, while the cool white is higher and offers more blues. You don't usually see it as being partly blue until you get over 8k or so, it just seems to get brighter white.

The color temperature does relate to the PAR, simply because bulbs with a different spectrums and photosynthetic pigments which can only use certain wavelengths, there will be differences in how much of the light can be used for photosynthesis - it's easier just to leave it out of the equation because the basics of light power can be determined by the type of light source, the rated watts, and extras like reflectors or higher performing ballasts. 54W means the bulbs draw 54W from the ballast, the ballast probably draws a few more to cover its own inefficiency, but given a wattage rating, a similar bulb age, and a competitive market - most T5s rated for the same wattage should give you similar growth. Stepping between types of light will factor in their relative efficiency: incandescent, power compacts, t5, metal halide, LEDs - in order of least to most efficient. Ultimately that means that 54W of T5 is more powerful (higher PAR, more light output) than an equivalent amount of power compacts or incandescent lighting, but less powerful than the equivalent wattage in metal halide or LEDs.

Old bulbs will produce less light, different kinds of ballasts will have different efficiencies and different drive powers (as mentioned for overdriving metal halides, but LEDs work similarly), and reflectors or optics can make a big difference into where your light is directed and ultimately how powerful it will be - including how quickly it dissipates at depth or distance from the center of the light, but to oversimplify and overgeneralize to the point of being little more than a math exercise, it would work out something like this:

10W PC = 7W T5 = 4W MH = 2W LED

I make no claims to the mathematical accuracy of this comparison and fully understand it could vary more than 30% in either direction easily just factoring in variances in equipment, but it's an easy way to think about the relative power of lighting and what a step up in lighting would offer you in terms of output.

Just remember:

The listed watts is their power consumption, not their light output

PAR is the measurement you need to worry about in terms of growth

Color temperature, at least in normal ranges, is about how it looks - not necessarily how it performs

Ballasts, reflectors, optics, shimmer effect, spotlight effect, actinic viewing, heat concerns, power consumption, price, etc. all play an important role in how you configure your system - every lighting option has it's benefits

[Christian]

Wow so much info thank you all for your help. I'm shure this will help newbes in choseing their lights for their fish tank. It helped me out on under standing how people get 3w per gallon.

Edited April 2, 2010 by christian

[mooric]

I thought the 3w/gal. rule came from the use of PC lighting, not sure it equates very well to other types of lighting.

[Timfish]

I thought the 3w/gal. rule came from the use of PC lighting, not sure it equates very well to other types of lighting.

Used to be 4-5 watts per gal in the early 90's when alot of people used T12 flourescents. This bugged me back then since Grolux were rated at 800 lumens and Chroma 50's and 75's were rated at 2300 lumens. This dates me even more but back in '88 there were some articles in Marine fish Monthly that set a target of 10,000 lux per square foot which I'm guessing morphed into the watt/gal rule.

[netmaster]

Well the stock thickness is easy, you just have to explain to joe blow the way paper 'weight' is determined by parent sheet size, and then they will totally understand why a 67#VB is around the same thickness as a 110# index, and both feel thinner than a 65# Cover. Oh, and the 80# cover is similar to the 100# color copy coated cover. I don't even bother anymore. <end print talk>

(sorry I have no input for the light question)

bunch of nerds( Im just joking) yall know too much about paper

[Timfish]

Here's a real interesting article looking at differences between 3 lighting setups and the associated coral growth of 11 coral species.

http://www.advancedaquarist.com/2008/3/aafeature1

What I find interesting is even though the corals looked better under 20,000K some showed better growth under 10,000K or T5s.

[Christian]

http://www.americanaquariumproducts.com/Aquarium_Lighting.html