Why 10000K ? That's too deep, right?

[six.line]

So I got a textbook from the university library on aquariums. (Dynamic Aquaria by Adey and Loveland)

I don't have the time to ingest it, so maybe what I'm reading is out of context, however much it makes sense.

Color temperature rating is the black body emission spectrum of light, and varies with depth of the water. 10000K is what light looks like at a depth of roughly 50 meters, according to the book. I didn't think most of our SPS/LPS corals existed that deep in the ocean. It seems to me that we'd want something around 6500K, as most reefs are shallow (10-20 meters)

Am I mistaken, if so, where?

I'm torn because of the student in me to trust a textbook, and torn on the other side because when I see your tanks (you experienced knuckleheads with too much money and too little student loan debt) your tanks look fantastic.

Help is appreciated.

 

[Highlander]

6500k will grow your coral fine, but it will look yellow in your tank.
10000k is much whiter and will still give you good growth.

 

[six.line]

So it's all about color?

Does that mean that the corals in our tanks look better than in davy jones' locker?

 

[six.line]

Hold it...

6500K -- higher than the sun (~6000K) -- and yet it's yellower than what is supposed to be white light?

I don't mean to question your knowledge, I'm just confused.

And isn't a higher kelvin rating also somewhat correlated to how 'blue' the light appears? Hence, the deeper in the ocean the bluer the water-- how could 10000K be whiter?

 

[SerLunchbox]

10,000K is at that point where it is basically the whitest possible then you get into the 14,000K range where it becomes noticeably bluer.

at about the 13,000/14,000K scale that is the point in which there is generally enough blue light within it to not need Actinic bulbs.

6500 bulbs are a white light, but not as brilliant as 10,000K

 

[Highlander]

<a href=showthread.php?s=&postid=6623487#post6623487 target=_blank>Originally posted</a> by chris.rogers
Hold it...

6500K -- higher than the sun (~6000K) -- and yet it's yellower than what is supposed to be white light?

I don't mean to question your knowledge, I'm just confused.

And isn't a higher kelvin rating also somewhat correlated to how 'blue' the light appears? Hence, the deeper in the ocean the bluer the water-- how could 10000K be whiter?

Check this out.
See pictures a bit down :
http://www.cnidarianreef.com/lamps.cfm

 

[six.line]

That is HUGELY helpful. Thanks for that link.

 

[dchao]

<a href=showthread.php?s=&postid=6623436#post6623436 target=_blank>Originally posted</a> by chris.rogers
So it's all about color?

Does that mean that the corals in our tanks look better than in davy jones' locker?

Hahaha, yes, it all about the color of your light bulbs. The zooxanthellae living in the polyps are responsible for collecting the light for photosynthesis. They do that by producing different color pigments. The other ability is that the zooxanthellae is able to block/reflect UV light (as they do in the reef), that's why many colorful SPS corals look fluorescent.

If you want you SPS corals to color up, then you have to have a lot of light in the UV spectrum. If you just have a 6500K daylight bulb for SPS corals, they will all look brown. 15,000K are now very popular amongst the SPS reefers now.

 

[dchao]

-removed due to double posting-

 

[Wryknow]

Any scuba diver can tell you first hand that most of the light that penetrates water is in the blue spectrum. I have a 10K bulb on my tank and it is MUCH whiter than the ambient light in even 100 feet of water (much less 50m.) Text books are great but there's no substitue for experience in most cases.

 

[jimbo045]

I am hooked on 14,000Ks. No deep look.

 

[Pandora]

Light is refracted by water, and when we say "yellow" or "blue", it's my understanding that this description is of how it looks underwater, after the refraction, not straight out of the bulb in air.

It's also my understanding (and please correct me if I'm wrong) that in some ways we in the coral trade & hobby are overcompensating for a lack of intensity we cannot reproduce in an artificial environment (no one can reproduce the number of lumens that the sun's energy can impart, big metal halide or not ). We do this through focusing on areas of the spectrum which excite specific zooxanthellae chloroplasts the most. In this vein, intensity as a quality of light has to be separated from spectrum/color temperature.

 

[jcraft]

if you want crazy growth, the 6500k bulbs are the ones to give it to you- a couple local reefers here are running 6500k Iwasaki's w/ VHO actinics and the growth is phenomenal!

A lot of people dont like the color though, so they tend to opt for 10k and up bulbs. Im running 14k bulbs on both tanks with no supplementation

so,
6500k- needs supplementation
10000k- may need supplementation, but not near as much
14000k- nice balance of growth and color- dont need supplementation
20000k- the bluest - may need white light supplementation, unless you like that look (personally i dont)

remember, none of our bulbs can compete with the sun, so what we're really looking for is a balance between good growth of our corals and aesthetics- we want it easy on our eyes

 

[fishman805]

What it all basically comes down to is simply this:"PAR"or Photosynthetic Active Radiation.... can we ( hobbiests ) reproduce nature in our tanks....? The answer to that question is: Not totally.... What we can do ( and strive to do ) is reach that goal...
We try it by using bulbs of all types of intensity and Kelvin ratings... Fact is, the best thing that we can do is provide the most that the current science can provide for a longer period of time.... Photsynthesis takes place in the blue and red spectrums and is reflected back as the green spectrum of light... Most organisims reflect back what they don't use as apposed to what they "do" use and absorb. What we see is the reflection of light that is not necessary for their health and well being....

Since most of us want to have a "pretty" looking reef tank, we tend to use lights that "accentuate" what we have in the tank rather than providing the correct light for the life that we've spent allot of our hard earned dollars putting into our little part of the ocean.... After all, who wants to look at a "blue" tank all the time?

But to do this properly, we have to provide the best lighting we have available for a longer period of time so that our corals will survive and thrive in captivity....

A 150watt light will penetrate to a certain depth... a 250 watt light even further and so on .... it's the "color" of the light that is important....

Bob