[Mattfish]

Also from our travels today, I learned that color temp affects growth and color viewing. What I heard:

• 6,500K promotes rapid growth, but not vivid color viewing
• 14,000K provides a balance between growth and color viewing
• 20,000K gives better color balance but is not as great for growth as 6,500K

Most of us are probably aware that the sun is between 6,000 and 7,000K, depending on where you are in latitude.

I realize many people have lights that put out only one of the above color temps, but with change of bulb or ballast can change to another. I'm tempted to figure out how to reset my light for a lower temp than the 20K I have now, something closer to 14K, to gain a little more growth on our corals. But I also understand that some life forms need the higher temp to survive. I need to go back and hit the books again, but....

Some thoughts and ideas on this?

[e_baer]

well, i think VAMAN would be the expert here, but ill give it a whirl.

as you know, light comes in wave lengths. the longer the wavelength, the deeper it penetrates through the water.

"normal light" is about i forget if it is 5500k or 6700k, but, either way it has a shorter wavelength than the actinics which are blue. so basically, depending on the depth of the coral, you need different types of light. now, in the natural reef, sps for example grow in shallow water, which means that they will need less k's. mushrooms on the other hand, will grow in deep water where only blue light will make it to that depth.

so the question is, what color/ temp do you use in an aquarium? i would say something in between. i use four 12000k and two 50/50's(1/2 actinic 420nm and 1/2 10000k)

with this combination, i get enought blue for color, but then also enough usable light by the higher light demanding corals.

I have also heard that the zooxanthallae that is grown in the tissue of the coral, will thrive much better under the higher k's, but dont hold me to it.

[NATIVEVAMAN]

the color temp of sunlight is 5778 (wikepedia)(kelvin)(color temp)I should first say that the color temp of 20k does nothing for coral growth and is entirly for the edification of the aquarist.Taking the purest view I would consider this to be cruelty to animals.They have a right to prosper and grow.If you have metal halide only I would recomend you look for something between 10 and 14k.The coral will get some growth and the tank will still look nice.If you have metal halide with florescent lights I would recomendsomething between 6500k and and 10k with actinic flourescents.Blue light is required by anemone's,corals and clams to support the symbiotic algea that helps feed them.However it is not a situation were if some is good so more must be better.At 20k there are instances of bleaching,this is when the sybiotic algea actually leaves the host and the host then starves to death.

[e_baer]

so, native, would you say i at least got some info correct?

[NATIVEVAMAN]

Elliot,you do better all the time.You have the right idea.A little work on the details and I am going to retire.

[Mattfish]

While cruelty to animals is a bit tough to hear - my Solaris is a commercially made product that is recommended, and no one's raised this concern yet, having the ability to vary my lights makes it easier to shift the color temp downward.

I'd emailed the owner asking for what settings would alter the color temp to something lower, but the response was change it how you like and not to a specific temperature. I'm not sure what that meant, but that's why I put this thread out.

Unfortynately, with no color temp meter (they're typically expensive, and it'd be a rare-use type of item, I'll try again to figure out how to set the light for a better temp.

As for coral growth, all of our corals are growing and are doing well under the light - our umbrella lather, octopus, palythoa, and many others have grown in size, so I suspect that animals adapt to conditions, a for-example being fish and corals that survive temp, pH and chemistry fluctuations.

[e_baer]

well, at least i am on the right track. a little more research and i think ill be ok.