10k vs. 20k

[eddie]

like i mention youd get just as good growth under 3 400 watt 20k as 2 400watt saki's with 360 watts actinic(mabey better with the 3 20k)just my opinion (im always sure to put (imo)
saki's are ok also i just think they suck for a display and wont recomend them
unless they are for mainly purple & blue domenated sps tanks
btw growth rate is awsome under 400 watt 20k also

 

[liquid]

Making a generalized statement about all coral light requirements based solely on chlorophyll absorption spectrum is not taking a look at the whole picture, IMHO. Not all coral have the same chlorophyll type, ratios, nor the same accessory pigmentation, which you have forgotten to reference in your post. According to a post by Eric Borneman on Reefkeepers:

http://www.escribe.com/pets/reefkeepers/m40791.html

Coral can contain any of the following in just about any ratio: "chlorophylla a, c2, peridinin, beta carotene,
xanthophylls, diadinoxanthin, zeaxanthin are the major photosynthetic
pigments and accesory pigments."

While there definitely is a valley between 500 and 600 nm in the chlorophyll absorption spectra for types A and C, also remember that accessory pigments can shield, absorb and/or re-emit light of different wavelengths and make these wavelengths available for zooxanthellae. I wish I could find the absorption spectrum of these accessory pigments, but the graphs are eluding me at present time.

For more information on how carotenoids function in photosynthesis, please see the following article: http://www.life.uiuc.edu/govindjee/papers/CarFin1.html

Here's another good article:

Lighting the Reef Aquarium - Spectrum or Intensity?
By Dana Riddle and Miguel Olaizola
http://www.advancedaquarist.com/issues/ ... eature.htm

Basically Dana, et al, found that intensity was more important than kelvin rating.

fwiw

Shane

 

[john f]

" I wish I could find the absorption spectrum of these accessory pigments, but the graphs are eluding me at present time."

I got this from a paper by Steve Tyree from '95:


Table 1 Extracted from (Jeffrey and Haxo 1968)
Absorption Spectra of Pigments from Zooxanthellae of Pocillopora sp.
Fraction Absorption maxima (nm) Identification
Fraction 1 - Orange 428,448,475 B-Carotene
Fraction 2 - Pale Orange 427,450,477 Unknown
Fraction 3 - Yellow 425,447,476.5 Diadinoxanthin
Fraction 4 - Yellow 418,441,469 Dinoxanthin
Fraction 5 - Pale Yellow 408,427,455 Unknown
Fraction 6 - Pale Yellow 420,440,465 Neo-dinoxanthin
Fraction 7 - Brick Red 475 Peridinin
Fraction 8 - Brick Red 465 Neo-peridinin
Fraction 9 - Pink-Orange Unknown
Fraction 10 - Blue-Green 409,428,663 Chlorophyll a
Fraction 11 - Light Green 448,584,634 Chlorophyll c





I think you can see that every accessory pigment has an absoption maxima in the 400-500nm range.
That's the reason Violet and Blue light are the most important for corals.



John

 

[john f]

Shane,
You should also read the forum for Advanced Aquarist. You will note that Danas use of the PAM fluorometer may have been incorrect and his conclusions wrong as well.


John

 

[liquid]

Interesting. Thanks for the heads-up. I haven't had time to keep up with all of the forums on AAOLM as I've been working on stuff for our website. I'm heading there now.

Shane

 

[liquid]

While it looks like there is some question as to the protocol used to run the tests, I am seeing that people are still agreeing that intensity outweighs spectral quality:

Eric Borneman: "Dana, ... I agree with the basic premise of your work...light intensity most assuredly is more important than spectral quality, and there are scores of papers to support it. I have no doubt that you got the results you did, and that there is some real value to what you found."

http://reefs.org/phpBB2/posting.php?mode=reply&t=16088

I also found it interesting that in that same thread that corals reacted to the testing conditions differently depending on what spectral quality they were acclimated under prior to testing:

Richard Harker (quoting Kinzie, et al): "While acclimation intensity had a pronounced effect (on photosynthesis), the results also showed that the color of the acclimation treatment influenced the photosynthetic responses of the corals. The color of the light used in the measurements of photosynthesis had much less effect on the photosynthetic response of the corals."

Specifically, the corals grown in blue and green light differed more than the corals tested under blue and green light. By testing one coral grown under 5000 K light and testing it under 6000 K and 12,000 K light you've just replicated a portion of Kinzie's 1987 study.

Interesting observations.

Shane

 

[Dana Riddle]

All,

Re: the PAM article in February's AAOLM - I'd like to take a opportunity to clarify some issues in the AAOL Forums.

Several advanced hobbyists took issue with the results of the experiment Dr. Olaizola and I conducted. Naturally, they are entitled to their own opinions (although I would appreciate data over opinion). As background,
Dr. Olaizola has researched the xanthophyll cycle (the same one found in corals) and has many papers published on the DD-DT cycle and PAM fluorometry. When I originally approached him with a protocol for the experiment, he reviewed it and made changes.

After publication, there were quite a few challenges to the results. Miguel was my resource for answers to technical questions at the time (a difficult task considering his workload and schedule). I've since purchased a PAM, and after studying the 3 manuals, consulting with the German engineers and a lot of practical application, I am in a much better position to answer any questions. I, and Miguel, stand by our results.

Dana

 

[saltshop]

I've since purchased a PAM, and after studying the 3 manuals, consulting with the German engineers and a lot of practical application, I am in a much better position to answer any questions. I, and Miguel, stand by our results.

A good starting point would be to answer the questions orginally posed in the AAOLM forum. The challenges were not based on the use of the PAM (I am sure Dr. Olaizola knows how to work the meter), but on the photoadaptation and acclimation of corals to different light fields over time. I am sure you could read the manuals as much as you would like, but do they explain what the animals response will be over an extended time to different light fields? That was the question originally asked by several and is still unanswered...what does taking a measurement of X coral at time=0 under light condition A and B have to do with reality in our tanks? Will the results be the same at time =1-365 days if kept under said lighting conditions on a continual basis?

 

[Dana Riddle]

JB,

Antennae pigments funnel harvested light energy to the PS II reaction center containing Pigment 680. It doesn't matter if the light is collected by chlorophyll A, C2, peridinin or any other accessory pigment - P680 is the gateway. Since the light produced by the metal halides in question is basically a white light (though the 12,000K is skewed towards the blue portion of the spectrum, but still contains significant amounts of red), I don't think we'll ever see the chromatic adaptations corals experience at depth in nature.

Miguel's livelihood depends upon his success in forcing marine algae to produce carotenes - and his opinion is that there aren't enough differences in artificial light sources to make a difference in rates of photosynthesis. Walz (manufacturer of the PAM) is of the same opinion and states that blue-enriched light acting as the actinic source *may* cause *slight* shifts in the ETR rate (as opposed to use of a red actinic source).

As a footnote, some reflectance experiements I've conducted show that excess blue light is simply reflected away from corals over a time course of months.

Dana

 

[pathos]

Hi guys,

I used to run a 10K 250W Ushio on my 65 gal reef. I recently switched to a 20K radium 250W (on an Icecap ballast) and I like it far more than the 10K. The color is a much more crisp blue. I find that it really brings out the colors better in my corals and seems to help prevent the growth of nuisance algaes. I also supplement with actinic VHO's and white PC's.

I personally prefer the 20K to the 10K. FWIW

pathos

 

[esmithiii]

Pathos: How you like the look and how your corals will grow are two different things entirely. Give us an update in 18 months.