Can someone explain PAR to me?

[Brad Villeggiante]

What is PAR?

Does PAR help with coral coloration i.e the higher the PAR the more the coral will color up?

I am running a Ushio single ended 250 watt 10K bulb and was told the XM 10K bulb is better because it has a higher PAR rating.

Are there any PAR studies that have been done on bulbs that are on the market and if so where can I find these studies to compare which bulbs are good and which may be crap?

[GTR]

http://www.reeflightinginfo.arvixe.com/

Will help to compare.

SteveU

[wasp]

Link won't work for me GTR !

[Brad Villeggiante]

It worked for me, great studies but I still need to understand how PAR affects colors.

[Brad Villeggiante]

Also I have a Cool Touch Lighting Ballast. Is this an alright ballast? I can't find any info on it on Cooltouches website. What studies have been done on this ballast?

[mesocosm]

Greetings All !

Are there any PAR studies that have been done on bulbs that are on the market and if so where can I find these studies to compare which bulbs are good ...

What Steve said ... http://www.reeflightinginfo.arvixe.com/ ... Great stuff, but it takes a little time to wade though ... IMO.

What is PAR?

Generally speaking ...

Photosynthetically Available Radiation (PAR)

Sometimes called Photosynthetically Active Radiation. Photon flux density (photons per second per square meter) within the visible wavelength range (usually 400 to 700 nm). It indicates the total energy available to plants for photosynthesis, and is thus a key parameter for biological and ecological studies.

Typically it is measured with a broadband detector that has nominally constant quantum response throughout the visible wavelength range, and nominal spherical angular response (to measure scalar irradiance). However the efficiency of photosynthesis is not constant for all wavelengths as implied by the definition of PAR. A much more thorough characterization can be obtained by measuring the spectral scalar irradiance with a spectroradiometer such as a HydroRad with scalar irradiance collectors.

Extracted From:
http://www.hobilabs.com/cms/index.cf.../1407/3241.htm

I have my own one-liners about PAR, but it's important stuff, and others infinitely more qualified than myself, say it so much better. I like Borneman's description when he talks about "Qualities of Light" ...

The following is extracted from: Aquarium Corals. Selection, Husbandry, and Natural History, Eric Borneman, T.F.H. Publications, Inc., 2001, pp. 328-329. :

... Light can be mesured by its spectrum, intensity, color temperature, and color rendition.

All the different wavelengths of light that correspond to certain colors together make up what is called the spectrum. ... Spectra are measured in terms of their wavelengths in units called nanometers (nm).

The intensity of light is a measurement of how much light energy, called photo flux, is available. ... intensity is measured in terms of irradiance. Irradiance is the amount of light energy (photo flux) that strikes a given area over a period of time, and is commonly described in units called lumens. The basic unit of measurement of the lumen is the lux, ... .

There are even more relevant measurements of light intensity known as Photosynthetically Available Radiation (PAR), and Photosynthetically Useful Radiation (PUR). These measurements, though fairly technical, are important since they correspond to the light that is potentially or actually useable by the zooxanthellae for photosynthesis, respectively.

PAR is generally defined as the amount of radiation (quantum flux) between 400-700 nm wavelengths of light that zooxanthellae could potentially use in photosynthesis. PUR is the amount of radiation that, according to pigmnet concentration, water clarity, etc., is actually available to the zooxanthellae.

Light is also measured in terms of color temperature. The units used to measure temperature are in degrees Kelvin (K). However, it is important to remember that the shorter wavelengths of red disappear a few feet underwater ... . Therefore, the color temperature of light actually gets higher (hotter) as the depth gets greater.

Color Rendition is a subjective measurement based on the perception of the human eye as to how accurately a light source renders the true color of an object. It is measured on a scale of 1-100, known as the color rendition index (CRI).

I left out the real scientific measurement unit of light initially, because ... other than being unfortunately irrelevant to the question ... it's the kind of techno-jibberish that most folks find annoying. Strangely enough ... IMO ... much of the confusion about lighting comes from the marketing strategies of marine lighting system and component manufacturers and their inexplicable fear of speaking the name of my absolute favorite scientific unit: The microEinstein. If we all discussed lighting in terms of microEinsteins, things would be MUCH clearer ... but maybe that's just me ...

...

[Brad Villeggiante]

So does that mean that the higher the PAR is in a certian color wavelength the more that color will come out in corals?

Ex: If a bulb has higher PAR in the purple wavelengths then the corals with purple in them will color up more?

[mesocosm]

Greetings All !

... but I still need to understand how PAR affects colors.

A little hobby history about the evolution of the discussion of reef lighting ... if you step into your DIY WayBack machine, and review the literature that hit the North American marine ornamental hobby between the mid-1970's through the early-1900's, everyone spoke in terms of lumens, and lux ... Spotte, Thiel, Moe, Tullock ... and an additional set of "lightweights" (... no offense ...) who wrote for TFH and Tetra Press ... Sprung and Delbeeck (... to a lesser, richer extent ...), and every light product manufacturer who sold things in North America. We had to start somewhere ...

Enter more advanced peer-reviewed literature in the mid-1990's. The science guys figured out that what was important to the energetics (... as opposed to color rendition ...) of coral growth was what the zooxanthellae were doing ... and what the zooxanthellae were doing was driven by the energy that they received from the light that struck the tissue they were embedded in. It's at this point that everyone began to stop talking about lumens and lux ... although folks like Hagen still include lux, lumen, Kelvin, and CRI numbers on most of their light products ... and started talking about PAR.

I bring up the history, because the next generation of terminology is already warming up on deck, sports fans ... PSR (photosynthetically stored radiation), PSU (photosynthetic unit), and PUR (photosynthetically useable radiation) are all beginning to emerge in the writings of Calfo, Fenner, Borneman, and others. Soon manufacturers won't have enough space left on their packaging ... hehe ...

...

... how PAR affects colors.

PAR levels can strongly influence coloration because it directly stimulates the production of, and relative abundance of, pigments within zooxanthellae that we can see directly. Pigments documented to be present in the zooxanthellae themselves include, "... chlorophyll a (blue-green color), chlorophyll c2 (light green), beta-carotene (orange), peridinin (brick red), diadinoxanthin (yellow)" ... among others (Aquarium Corals, Borneman, 2001, p.52).

But it's not that simple ... of course. The coral animal itself produces some interesting stuff ... in different places. And since zooxanthellae are intimately connected with the development of tissues and skeletal structure, so too is PAR related as well.

(*) Some non-zooxanthellae pigments from the soft tissues of corals:

astaxanthines & related compounds (pink-orange)
ketones, carotenoids & xanthophylls (orange-red)
phoenicoxanthin (pink)
astaxanthines, carotenoids & xanthophylls (deep orange)
carotenes (yellow-orange)
melanin, purines, astaxanthin, ommochromes (brown)
astaxanthines (white)
porphyrins & bilines (green)
carotenoids, flavines, astaxanthines, metridene,
xanthophylls & ommochromes (red)

(*) Some skeletal pigments of Stony Corals, Hydrocorals, and Gorgonians:

carotenoids (yellow-orange)
astaxanthines (pink-orange)
astaxanthines (pink)
astaxanthines (purple)
astacene & xanthophylls (orange)

(*) = Extracted from:
Aquarium Corals. Selection, Husbandry, and Natural History,
Eric Borneman, T.F.H. Publications, Inc., 2001


You can go a little nuts with this stuff ... Lord knows I have ... and I haven't even started ranting about light refraction through protein strands & complexes, nor have we touched on cryptic coloration, or aposematic coloration adaptations (... defense and camoflague patterns ...).

Are we having fun with PAR yet, Brad?

hehe ...

JMO ... HTH

[Brad Villeggiante]

great fun!

[GTR]

I have those books but every time I read those parts it makes my brain feel like it's got a wedgie.

SteveU

[mesocosm]

Greetings All !

Out of sync ... sorry about that ... can't type fast enough ... damn internet technology ... where is the instantaneous heuristic discussion forum software when you need it?

So does that mean that the higher the PAR is in a certian color wavelength the more that color will come out in corals?

The higher the PAR, the more energy and cellular products (... with their associated colors ...) are produced by the zooxanthellae. Additionally, the more energy & cellular products the zooxanthellae produce, the more energy and raw materials the coral animal has available for growth ... and so on.

In addition to the qualities of the light source (... spectrum, intensity, heat ... etc ...), it is the chemical composition, relative abundance of those chemicals, and the cellular structure of both the zooxanthellae and the coral animal which determine the characteristics of the light that is reflected back to our eyes (... perception of color ...).

In other words, it's not just about the qualities of the light source, it's also about how the light from the source is altered (... reflected and/or refracted ...) by the tissues and cellular components of the coral animal and zooxanthellae. It's this "altered" light striking the rods and cones (... the light energy receptor cells ...) in our eyes which generates the sense we describe as "color." Both light source characteristics AND the cellular characteristics of the coral animal and its zooxanthellae interacting together determine how cool a specimen "looks" ... along with things like water clarity.

Ex: If a bulb has higher PAR in the purple wavelengths then the corals with purple in them will color up more?

There are two things going on ... (1) Fluorescence:The way that light is refracted (... "bent" ...) by the chemicals within the tissues and skeletal structure; (2) Photoadaptation: The production and/or change of chemicals over time within the tissues and skeletal structure ... either by the zooxanthellae, or by the coral animal.

First issue ... fluorescence. A pigment can refract light differently, depending on the wavelength of the light that strikes it. A 10K light source might cause the pigment to appear "purple." A 20K light source can cause the same pigment to appear as a "rich, glowing purple" ... because of the difference in the way that the pigment refracts 20K light. That's a hypothetical example of fluorescence. It could be said that the 20K light source caused the coral to "color up" ... although I'm a little uncomfortable with the phrasing.

Second issue ... photoadaptation. After switching to a higher PAR rated bulb, the zooxanthellae may begin to produce more of the pigment(s) which appear to us as "purple." Over time, more of those pigments accumulate within the specimen's tissues. Over time, one might perceive "more" purple ... greater intensity of purple ... compared to the moment when the bulbs were switched. It could be said that the higher PAR rated bulb has caused the specimen to "color up."

While it is true that higher PAR rated bulbs can enhance fluorescence ... because of the "better" bulb's inherent qualities ..when I start toying with higher PAR bulbs, I'm usually trying to tinker with the long-term photoadaptation pattern/chromoprotein composition of my specimen(s) as the way to get better colors over time. If I want the pigments that already exist within the coral to "be all they can be" ... I slap on some extra actinic03 light sources above them, and call it a day.

As to issues involving which ballasts work better with which lights ... I am currently a complete lame ... others are much more qualified to answer those types of questions.

Acquisition of cutting edge knowledge from people with serious expertise ... it's one of the many reasons why I love this website ...

...

JMO ... HTH

[Aged Salt]

Excellent posts, Gary.My oversimplied explanation of coral coloration may give a glimpse to the complexity of this subject It's important to remember that the coral colors we see under captive lighting are a result of the combination of the zoox's. photosynthetic pigments & the coral tissue fluorescing pigments. Every coral has different zoox which in turn, have different pigments[chlorophyll, carotenoid, peridinm] varying in amounts based on the locations the corals are collected.
UV radiation blocking pigments[pocilloporins,mycosporin-like AA's] are implemented by the coral tissue to protect the polyps of the symbiont[zoox]. There are many types of these pigments, which when excited in their reactive state, fluoresence. It's helpful to know that the zoox. tranfers energy to the host coral while the coral's pocilloporin reflect it.This is the case in nutrient-poor environments. So coral coloration is a complex checks & balances. Corals will change color with changes in light intensity[photo flux], whether it's by more dense photosynthetic pigments or increased fluorescence from the production by the coral's chromophores.Bob

[gqjeff]

I know when I went from CV 14K to xm 20K the corals looked much better.. Then when I added the t5 blue plus and the uri vho actinics on my ic660 they REALLY popped... I am going to toy with adding 2 10K on one side of the tank and see how they look.. I will def be posting pics when I do this of both sides 20k with supplimentation and 10k also......

[mesocosm]

Greetings All !

... I will def be posting pics when I do this of both sides 20k with supplimentation and 10k also ...

gqjeff,
You post any more pics like the ones you did in the "Moment of Truth ..." thread, my brain is going to explode ... they are simply freakin' awesome !

For those of you who haven't seen them yet, check out ...
http://www.zeovit.com/forums/showthr...9808#post19808

[gqjeff]

Gary, TY very much.. Yea those would be the corals I would be photographing again heheh.. I would just like to run them for a couple month and maybe see if growth had improved on that side of the tank.. hard to beat the colors I am getting with the combination of lights I am runing now.. I will say the t5 blue plus and the uri actincs REALLY made my corals perk up in color...