Purchasing Lights relative to wavelength not color?

[Funky_Fish14]

Hello everyone!

Well, I have limited knowledge on the physics of 'light' seeing as I am only in Grade 10, however I have done fair bit of reading relating to the different aspects of light usage and ratings. My conclusion so far seems to be that it would be better to purchase lighting systems applying the correct peak wavelengths for your corals use, and then choosing the CCT(Correlated Color Temperature) relative to what you want to 'see'.

I see that typical optimal 'violet/blue light' conditions in most reefs include wavelengths of between 420-460nm. 420-440nm being in the 'violet' range, and 440-460 in the 'blue' range. I also read that some reefs seem to receive or can benefit from light wavelengths in both the 'green' (490-540nm) and 'yellow' (540-590nm) spectrums.

We purchase our bulbs relative to the 'PAR' (Photosynthetically Available Radiation) (Measured in PPFD, Photosynthetic Photon Flux Density) they seem to put out, as well as the CCT we prefer.

It seems to me what we should look at in a "good bulb" (one that would satisfy the coral's lighting needs) is not just the PPFD measurement, but also the distribution of the wavelength spectrum. Preferably a bulb maximinzing PPFD/PAR in the 420-590nm spectrum, with empasis on the 420-460nm portion. Typical reef water surface sunlight seems to peak between 450 and 600nm, which would drop through penetration of the water, thus this seems to make sense of my above conclusion.

The rest, basically the CCT, should be a matter of personal preferance/opinion on the 'color' we see produced by the bulb and how it affects our coral's coloration.

I guess this is just a bunch of babbling, but to me, this is what I will concern myself with on my next lighting purchase.

ANY input discussing any of these points would be fantastic!

Thanks for reading!

Chris

 

[horkn]

make it the way you want it, the corals will adapt

 

[Funky_Fish14]

....Maybe you might not want to optimize your corals growth/lighting quality levels, but smart remarks arent the point of this forum.

Proceeding my readings, I found Sanjay's spectral plots, and they have exactly the info that IMO should be used to purchase a light. CCTs appear to be alot lower than they 'claim' to be on the bulbs we buy, so maybe we should just use actinics/blue/yellow to adjust color preference, after finding the light offering the needs we want?

Chris

 

[Gudwyn]

Funky,

"My conclusion so far seems to be that it would be better to purchase lighting systems applying the correct peak wavelengths for your corals use, and then choosing the CCT(Correlated Color Temperature) relative to what you want to 'see'."

The interesting thing is that those peaks dictate what you see. And they do it in multiple ways:

1. The difference in peaks changes the color of the light as you see it. So it changes the reflected light.

2. The difference in peaks changes what flourescing pigments in the corals are activated. So it changes the way the color looks.

3. The difference in peaks change the pigments produced in the corals.

It's almost impossible to predict how your particular corals will respond to your particular combination of lights, ballasts, flow and nutrients. Well from a color perspective. From a growth perspective, PFFD really does seem to be fairly close to accurate in my experience.

BTW. You are correct that marketing terms like 10k, 14k, 20k, etc. are generally useless. Look at the spectral plot.

My current bulbs are a reeflux 10k. And other than a little pink, they look pretty close to my prior hamilton 14k. And before that I ran ushio 10k's which were fairly yellow.

But the growth from the ushios and the reeflux is pretty similar and significantly higher than the hamilton 14k. All on 250w DE icecap electronic ballast.

I was able to find the reeflux 10k by comparing spectral plots and keeping in mind that I wanted something similar to the 14k hamilton with a little more red and a lot more PAR. So the plots are super useful.

But there is no way to pick the "best" bulb. Doesn't exist.

 

[Fiziksgeek]

I have a pretty good knowledge regarding the physics of light as lasers are my career. I think Horkn has a valid point, and the remark did not seem smart to me. When picking a bulb, you must take into account many factors. But lets face it, if you hate the color of bulb you choose, it doesn't matter much how fast the coral grows, you will be unhappy with the set-up. When people are unhappy with their tanks, they tend to neglect them, and the tank goes down hill....I would rather have a less then ideal lighting configuration (for coral growth), and a successful system that I love looking at and working on.

 

[Funky_Fish14]

I did add that I thought we could simply use other lighting to adjust the color we see, or the color the coral producess, to make it taylored to our preferance.

I also never said 'best' bulb... but a 'best' bulb would be the 'best' fitting bulb in one's opinion.

But I guess.... it doesnt really matter.. lol