losing sanity over 'full spectrum' discussion

[blasterman]

{Maniacal laugh of frustration}

 

Ok, the below is a graph of a 20k metal halide used for reefing. .I'd say radiometrically about 90% of the energy is between 440-460nm, if not more. Any debates on that please chime in. I know what my college physics prof would say.....

 

Somebody not as tired as me please explain to me how this is an example of 'full spectrum' because there's bits of energy here and there above black body. I would classify it as darn near monochromatic...and it grows corals just fine. That was my point.

 

 

 

 

[CJJon]

Corals don't get or need full spectrum sunlight (and you will be hard pressed to simulate same with a bulb). So they are trying to hit the sweet spot of light that your livestock use the most. The graph looks near full spectrum to me although there is a strong peak at 450nm (which is most useful). Read the bulb description.

 

• OUR BEST! Bright ice white blue appearance
• Ideal Choice for Marine and Reef Aquariums
• Outstanding intensity and color with a high PAR value light
• Simulates sunlight at ocean depths of 8-20 feet
• Promotes the development of photosynthetic plants, anemones and coral
• Intensifies the natural vibrant fluorescence in fish, coral and marine life
• Full spectrum consisting primarily of high spikes in the 440-460 nanometer range with additional smaller spikes in 550, 590 and 690 nm range
• Use with 250 watt Magnetic ballast with ANSI code M58 or 250 watt Electronic ballast

Also, take a look at this page: http://www.advancedaquarist.com/2012/10/aafeature

 

"As we have seen, formal parameters such as CRI and CCT are not very useful for determining whether a particular light fixture is suitable for a reef tank. At the same time we need to point out again that sufficient power in the 400-480nm wavelength range is critically important. If this condition is fulfilled, other parameters of the light fixture may be selected based on the owner's individual preferences (just make sure that the total radiated power does not exceed the recommended values). We have to admit, unfortunately, that most of the commercially available light fixtures today are only utilizing the 450nm range and above, whereas an ultimately important range between 400 and 440nm is usually left out, or is inadequately represented."

So, it looks like the bulb could be better at providing 400-440nm, but has the main 450nm peak covered. You don't need a full spectrum light, just one that has strong output in the 400-480nm range. The rest is esthetics.

[Nano sapiens]

I think you are visualizing 'Full Spectrum' as the spectrum that the sun provides at noon on a clear day at the water's surface, in particular. Obviously, there are large spikes of the various wavelength than we think of as 'Fullness' and it is a much different spectrum than what we see here with a 20K MH (which is meant to simulate the light field at some depth in the ocean).

 

Perhaps a better term would be 'Complete Spectrum' which doesn't infer a quantity to the various spectra, but rather that a multitude of wavelengths are present.

 

CJJon - That excellent article is my 'go to' for light related topics. So nice to have just about everything we need to know about light for our corals in one convenient place.

[Horerczy]

I prefer Dana Riddle's article on the subject

http://www.advancedaquarist.com/2014/5/aafeature

[blasterman]

The graph looks near full spectrum to me although there is a strong peak at 450nm (which is most useful).

 

 

The residual energy other than 440-460nm is, from a biologic standpoint pretty much radiometrically irrelevant with a 20k reef bulb. Or eyes see just enough of the other energy peaks so we don't perceive it as nearly monochromatic as a royal blue LED, but a coral almost certainly can't tell the difference.

 

Again, I really have an issue with this term 'full spectrum' because it has no formal advertising value or scientific, yet it's tossed about by advertisers and taken up by reef shop workers and forum bantering that conffuses more than clarifies. The nitwits selling high CRI fluorescent tubes are the worst abusers. Ever see a 98CRI fluorescent tube on a spectrometer? "Full spectrum" my butt. The spikes just hit the plots on a CRI chart, and ignore everything else.

 

I'll post a link here to the spectrum of a typical Higher Pressure Sodium bulb. You know, the pink/yellow things over roads at night that are gradually getting displaced by LED because their narrow spectrum hurts visibility? The peak spectrum range of the HPS is actually wider than the 20k reef halide, and it's secondary peaks are actually higher. So, who here wants to call a HPS bulb 'full spectrum? If we define the 20k halide as 'full spectrum' then the HPS must be 'fuller spectrum'.

 

So, it looks like the bulb could be better at providing 400-440nm, but has the main 450nm peak covered. You don't need a full spectrum light, just one that has strong output in the 400-480nm range. The rest is esthetics.

 

Thank you! (sigh of relief that I was losing my mind trying to this across). Yeah...the coral really only cares about deep violet to blue, and it's pretty much all cumulative anyways. Extra colors are for our sake..not the coral's. I really think this needs to be stressed more in this forum.

 

Perhaps a better term would be 'Complete Spectrum' which doesn't infer a quantity to the various spectra, but rather that a multitude of wavelengths are present.

 

 

Works for me. I'm seeing too many posts regarding the newer multicolor LED units as being superior to other units because they are 'full spectrum'. You have color flexibility, but it's not superior for coral growth -vs- the old school classic cool white and royal units.

[Nano sapiens]

Works for me. I'm seeing too many posts regarding the newer multicolor LED units as being superior to other units because they are 'full spectrum'. You have color flexibility, but it's not superior for coral growth -vs- the old school classic cool white and royal units.

 

Not superior in growth, perhaps, but can be superior in the sense that some of the addition wavelengths stimulate the production of various fluorescent and non-fluorescent pigments...and make them properly visible to our eyes.

[cromag27]

Anyone else tired of seeing cartoon blue tanks?

[Nano sapiens]

Anyone else tired of seeing cartoon blue tanks?

 

Oh man, don't get me started...

 

Unfortunately, many of the LFS's have followed the trend as well since it makes it easy to sell a so-so coral as it just needs to fluoresce under actinics.. Makes it difficult to know what you are REALLY getting until you get it back home and put it in your tank...

[Horerczy]

Bring a white halogen flashlight with you and shine it in the tanks.

[Nano sapiens]

Bring a white halogen flashlight with you and shine it in the tanks.

 

Yeah, that'll work. Just making a point as I don't buy much for my fully stocked little nano.

[fredfish01]

Full spectrum with respect to aquarium lighting is a misnomer. It is a marketing invention to create a 'gold standard' label to sell against (only our lights are full spectrum. Everything else is inferior...). I've seen this done very effectively in other industries. It is a marketers wet dream to create a word/phrase that comes to define the 'gold standard' for that product. It's a license to print money.

 

In the endless Chevy vs Ford lighting debate it has become an easy way to silence your critics.

 

The residual energy other than 440-460nm is, from a biologic standpoint pretty much radiometrically irrelevant with a 20k reef bulb...

 

I would be equally careful of the claim that the photosynthetic marine organisms we maintain require nothing outside of 440 to 460nm. We actually know very little about the requirements of that which we keep.

[blasterman]

I would be equally careful of the claim that the photosynthetic marine organisms we maintain require nothing outside of 440 to 460nm. We actually know very little about the requirements of that which we keep.

 

 

Probably...maybe.

 

The thing is.....the people selling the Chinese LED arrays with 15 different disco colors aren't doing so from the basis of scientific study either. Agreed?

 

Bring a white halogen flashlight with you and shine it in the tanks.

 

 

 

Yeah...I hear that. Local shop with a nice selection of LPS including some rare Acan varieties had some Radion knock-offs turned up with so much royal you coulnd't distinguish varities. I had to come back in the middle of the week because that's the only day the right knuckle-head was working with his smart phone app to dial in the lights to non-retard mode.

[fredfish01]

 

Probably...maybe.

 

The thing is.....the people selling the Chinese LED arrays with 15 different disco colors aren't doing so from the basis of scientific study either. Agreed? .

I'm sure they are not. Thing is, there is a tendency to assume that because it looks good to us, it is good for the coral. 20K lights make corals look good, so those must be the best lights for corals.

[blasterman]

Some background on this post:

 

I posted this after being pretty much accosted by an admin on a local reefing forum who had an anti-LED agenda, and was trying to push it with carefully concocted straw horse debates.

 

Resident LED fans were being pretty pushy about the only LED lights you should be buying are the full spectrum ones...for reason we've pretty much debunked above. So, I get caught in the middle trying to debunk both sides. When you're trying to teach basic lighting science to a bunch of nitwits who think because they work in a reef shop that they suddenly have BAs in marine biology and also have admin rights you are bound to lose.

 

I figured correctly we can hash out the truth here...as usual.

[fredfish01]

Some background on this post:

 

I posted this after being pretty much accosted by an admin on a local reefing forum who had an anti-LED agenda, and was trying to push it with carefully concocted straw horse debates...

Now the maniacle laugh makes sense.

 

My personal feeling is that people put too much weight on lighting, often attributing husbandry issues to the lighting.

 

I think a lot of what is needed for LEDs is already figured out, folks just are'nt ready to accept that yet.

[cromag27]

so what is the consensus on which colors of leds are beneficial for coral? do we really need green, red, orange, etc?

[fredfish01]

Cromag08. Take a look at the sticky at the top of this forum titled LED Colors, And What They Are Used For It lays things out very well.

[cromag27]

Oh nice, thanks. but it doesn't mention which combination is require to achieve a 'full spectrum'.

[Horerczy]

That's more because manufacturers just bandy the term about willy nilly with no set base for comparison than anything else.

L