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chindapol
03/23/2006, 05:33 AM
Hi Sanjay,

I got a few question regarding the spectral anaysis

1.) Why there are no CCT data for 2000K bulb? Also in most of the major manufacture specification stated wavelength instead.
e.g. http://www.venturelighting.com/On-LineCatalog/Specialt.pdf
MH 400W UBDX contain dominant wavelength of 462 nm. which fall in most of the same category as other 20000K from your data.

In a contary, a of plot Hamilton 400W 14000K SE 1 PFO 400W HQI N 140 have a CCT = 34583 which exceed manufacture 14000K. Therefore, what's the scientific relation between actual CCT and spectrum information. (I am thinking of Wien's Displacement Law) If you have more peak lampda, the overall temperature may increase. Please corect me.


2.) So 10K is the most efficient bulb because not only it produce better PPFD but also those PPFD occurs in a usefull range of spectrum (eg. 420+540-580) thus compensate around 15-20M of ocean water. Correct?

Thanks

Sanjay
03/23/2006, 10:01 PM
<a href=showthread.php?s=&postid=7020961#post7020961 target=_blank>Originally posted</a> by chindapol
Hi Sanjay,

I got a few question regarding the spectral anaysis

1.) Why there are no CCT data for 2000K bulb? Also in most of the major manufacture specification stated wavelength instead.
e.g. http://www.venturelighting.com/On-LineCatalog/Specialt.pdf
MH 400W UBDX contain dominant wavelength of 462 nm. which fall in most of the same category as other 20000K from your data.

In a contary, a of plot Hamilton 400W 14000K SE 1 PFO 400W HQI N 140 have a CCT = 34583 which exceed manufacture 14000K. Therefore, what's the scientific relation between actual CCT and spectrum information. (I am thinking of Wien's Displacement Law) If you have more peak lampda, the overall temperature may increase. Please corect me.


2.) So 10K is the most efficient bulb because not only it produce better PPFD but also those PPFD occurs in a usefull range of spectrum (eg. 420+540-580) thus compensate around 15-20M of ocean water. Correct?

Thanks

Most the "blue' lamps in reality do not have a Correlated Color Temperature. In reality that CCT is infinity.. but in my data I have them as 0. Most of the blue lamps being sold in the hobby are like these architectural lamps.

The high ccT you are seeing for some the lamps...well that is the calcuated value based on the x,y coordinates for teh color. The CCT is basically closest point on the CIE color chart on the Black Body locus. the Black body locus is highly non linear especially towards the end. So a slight difference in x,y coordinates can result in large changes in CCT.

I am in the process of writing up a article in the series on CCT, what it means and how its computed.

2) This is not an easy question to answer and there is no simple answer. Corals have been shown by aquarist to grow in a wide range of color temperature lamps. What is known is that there seems to be some positive relationship between higher PPFD and coral growth (upto some point - obviously). Higher PPFD over a wide spectrum does result in higher growth rates. Most of the time the higher PPFD lamps are around 6500K. But this tends to look yellow to a lot of people. So 10000K is a compromise between the yellow look and the blue look while providing a good amount of PPFD.

As to matching the bulb spectrum to the coral spectrum.. that can be done if you can get some good absorption spectrum of the corals. With the one absorbtion spectrum curve that I have... I found that lamps with higher PPFD also have higher Photsynthetically useable radiation.

Another fact that complicates the determination of the optimal is that the corals also adapt.

sanjay.

chindapol
03/24/2006, 12:40 AM
Thanks for answer! Looking forward to see your next artical.

I like the definitive answer about the fact about 10K color temperature.