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dark_stranger
23-03-06, 09:00 PM
I now have a spare 4ft, 216watt (4 x 54 tube) over tank luminaire light unit & am considering using it for a frag tank. Do Corals need blue light as I am considering the tube combination, ie. 4 whites = 4 x 54watts resulting in 216watts, or a mixture of whites/blues?

philfish
23-03-06, 09:03 PM
Corals don't need "blue light" as such. the reason we use blue lights is more that it is aesthetically pleasing to the human eye. Corals ideally need the lower end of the spectrum, with lights of around 6000 to 8500 kelvin as an ideal. These lights usually give off more of a yellowy look to our eyes.

popsock
23-03-06, 11:56 PM
I would disagree with that, I think Phil you're thinking of Halides where the nearer to sunlight, the higher the PAR. As Stuart is talking about tubes that rules does not apply. If two lamps both output the same PAR (as you'll find most flouescent tubes do regardless of colour) then the blue light (actinic) will punch deeper through water than the white light will. The deeper your tank, the more effective Actinic light is.

Keith_Man
23-03-06, 11:57 PM
I disagree... corals do require blue light..more so than other colours as this is what most corals have evolved to recieve. zooxanthellae is naturally golden brown in colour and this also happens to be the colour that absorbs blue light best. Blue is also the dominant colour after about 3m under water...

What lamps are you using? your white lamps MAY have enough blue light (wavelength) for the coral to use... so adding blue lamps as per philfish is kinda for aesthetics.

However, If it was me... I'd go for 1:1 mix of blue/white lighting..

philfish
24-03-06, 12:19 AM
Didn't mean to confuse you. I was indeed talking of MH and you are talking about flourescents.. And the guys are both quite right. It's the blue end of the spectrum that manages to reach further into the wtaer. What I meant was that actual blue lights are not needed, it depends on the amount of light in your bulb.

Sorry to confuse the issue.

popsock
24-03-06, 12:23 AM
Keith, you're obviously entitled to your opinion, but the greatest minds in marine aquatics at this time all agree that the level of Photosynthetically Available Radiation is what is most important to corals, and that the colour of light doesn't matter whatsoever.

Cheers
Andy

Keith_Man
24-03-06, 12:37 AM
Originally posted by popsock@Mar 24 2006, 12:23 AM
Keith, you're obviously entitled to your opinion, but the greatest minds in marine aquatics at this time all agree that the level of Photosynthetically Available Radiation is what is most important to corals, and that the colour of light doesn't matter whatsoever.

Cheers
Andy
<div align='right'><{POST_SNAPBACK}> (index.php?act=findpost&pid=163538)[/quote]

I have always thought that the sectrum plays a role... whilst the level of output is of equal important. If a coral has developed/evolved the pigments to optimally absorb a specific spectrum... wouldn&#39;t it be wise to provide it? would you be wasting energy by providing lighting of the incorrect spectrum?

I guess corals may be able to absorb all colour of the spectrum (some better than others)...so they may not necessarily NEED one colour... but in the case of blue light and corals, I think it would be best to provide it

http://www.reefpark.net/forums/style_emoticons/<#EMO_DIR#>/006_grin.gif JMO

Edit: Here&#39;s an article I found by Sanjay Joshi: http://www.personal.psu.edu/sbj4/aquarium/...tosynthesis.htm (http://www.personal.psu.edu/sbj4/aquarium/articles/Photosynthesis.htm)

According to him, both spectrum and intensity/output are important.. However, fortunately for us corals can and will adapt http://www.reefpark.net/forums/style_emoticons/<#EMO_DIR#>/027_wink.gif

Frunkster
24-03-06, 01:20 AM
Ricordia for 1 need blue light (IME) to come in to their own.

I plann to supliment my 250watt (650 to 10kbv)MH&#39;s with both t8 blues & t5 pure actinic&#39;s in my new set up, for both myself (the t8 blues) & the corals 650kelvin MH&#39;s & pure actinc&#39;s.

Would this be a step in the right direction guy&#39;s? (sorry for the partial highjack).

philfish
24-03-06, 07:42 AM
Well Frunk, I&#39;ve got pretty similar to what you are suggesting 250w MH with double actinics, and my Ricordia are thriving. They are at least 8 times the size of when I got them 6 months ago, and are dividing. Dunno if the light has made a difference, as there isn&#39;t a way to compare them against rics. that didn&#39;t get that light. But it&#39;s certainly done them no harm.

crazi fish
24-03-06, 10:09 AM
Originally posted by Keith_Man@Mar 24 2006, 12:57 AM
I disagree... corals do require blue light..more so than other colours as this is what most corals have evolved to recieve. zooxanthellae is naturally golden brown in colour and this also happens to be the colour that absorbs blue light best. Blue is also the dominant colour after about 3m under water...

<div align='right'><{POST_SNAPBACK}> (index.php?act=findpost&pid=163519)[/quote]

i agree with Keith, in fact the reason zoox looks brown/orange is because it absobs blue light so well.

grass is green as chlorophyll absorbs blue and red - but reflects green light and thats what our eyes see.

magic http://www.reefpark.net/forums/style_emoticons/<#EMO_DIR#>/027_wink.gif

Keith_Man
24-03-06, 10:32 AM
Originally posted by Frunkster@Mar 24 2006, 01:20 AM
Ricordia for 1 need blue light (IME) to come in to their own.

I plann to supliment my 250watt (650 to 10kbv)MH&#39;s with both t8 blues & t5 pure actinic&#39;s in my new set up, for both myself (the t8 blues) & the corals 650kelvin MH&#39;s & pure actinc&#39;s.

Would this be a step in the right direction guy&#39;s? (sorry for the partial highjack).
<div align='right'><{POST_SNAPBACK}> (index.php?act=findpost&pid=163547)[/quote]

Yes, sounds good, but IMO dont go too heavy on the 6500k. the extra red/yellow lighting will help enhance warmer colours but in IMHO, dont let it dominate. I would stick to lamps that peak within the 400-500nm spectrum as per Sanjay Joshi&#39;s:

"The pigments in the cells will absorb different wavelengths with different efficiencies. The absorption spectrum for zooxanthellae has been shown to have a broad peak in the 400 to 500 nm waveband (blue-green) and a narrow peak in the 650 to 700 (red) waveband. "

and IMO he is probably one of the current greatest minds in reef lighting