Light is light???

[Stolireef]

We've all read numerous threads debating T5 vs. MH vs. LEDs. Lots of anecdotal reports of successes or failures with all three. With that in mind, I have a questio about light itself.

If I take a precise measurement of both PAR and wavelength from, say, a 400W Radium MH and duplicate those exact measurements with a combination of LED's and either lenses or reflectors, wouldn't the light be exactly the same? Wouldn't it be like mixing paint to achieve specific colors? I use the MH vs LED since they are both point sources of light as opposed to the T5s.

The only thing I can think of that would make a difference would be the fact that LED's are what I would think of as a digital source of light. In other words you have specific wavelengths associated with each LED and achieve the same measurements by blending. MH on the other hand are what I would call analog light in which the wavelengths are determined by the phosphors in the bulb.

This is science question rather and is not meant to start another debate on what works best so I'd appreciate some scientific answers.

Thanks.

 

[Ron Reefman]

All light is photons, but not all photos are the same (different wavelengths and energy) . But IMHO, you are right in that, for the most part, light is light. And yes, you can make an led fixture that would look the same to a PAR meter or a spectrometer as a t5 or MH. But that isn't reality, is it?

The real difference is that MH and t5 make light and throw it out in all directions, that's why they have reflectors and not lenses. The led sends light out in a narrow 120 degree beam which some fixtures collect and narrow down even more to 90 degrees. So MH and t5 light is bouncing all over the place and led light is very directional, not a laser, but kind of laser like. That means it makes darker shadows under ledges and overhangs and doesn't get under some corals as well as MH or t5. But that about the only difference in the light that makes it to the tank.

Think of it this way, MH and t5 is an unruly mob of photons that are being herded toward the water. The led light is a grade school marching band that goes thru a lens and becomes a military marching band, very orderly and in a straight line.

All 3 work and all 3 can grow healthy coral. But the 3 fixtures are so different in terms of their advantages and disadvantages. It isn't about the light in the tank... OK, maybe a little. But the differences are heat, cost to run, cost to replace bulbs and ability to control the light in terms of intensity and color without doing bulb changes.

 

[Bronx19]

A diode is made to produce one wavelength of light, which then requires you to put a handful of colours into your unit to attempt to cover the critical wavelengths corals use. One of the biggest upsides of T5 is the massive range they cover through the spectrum. However, light of a given wavelength is the same no matter what it comes from.

 

[Stolireef]

Thanks so much for the thoughtful and thankfully, non-partisan responses. If I understand correctly, the lenses (Ecotech perhaps) and reflectors (GHL I think) are designed to blend the colors of the LEDs. When you blend the LED colors, does that create a wider variety of wavelengths? I keep coming back in my very simple mind to blending of paint colors or, for those of you who remember Tidy Bowl, yellow and blue make green. In other words, with a wide variety of LED colors, can you make a huge variety of wavelengths?

Sorry if I'm being thick about this.

 

[oreo57]

White LED "blend colors" internally by using phosphors.. Same as T5's ect

monochromatic LEd's are then added to 1)make a look and 2)hit certain "important" wavelengths 3) fill "holes" in the led phosphor "package" themselves.
#3's holes are technically unnecessary but is more cost/acceptance thing.

Violet based emitter w/ RGB phosphors (not really different than t5s which use RGB phosphors but have added "spikes" due to using the emission spectrum of Mercury to charge and emit..

The color channels of current LED's serve 2 purposes 1)add par and 2) add a "look"..and 3)add dynamic modes i.e sunrise/sunset, moon phases ect.
One last graph 6500k MH..NOTE that that YUJI High CRI has a pretty close match in spectrum to the MH..

I suppose one could add some choices also try to emulate light at depth due to light attenuation..though few include cyan/green.

guess I didn't really answer anything you asked..

When you blend the LED colors, does that create a wider variety of wavelengths?

No, you can't exactly create any "new" spectrum that I know of.. Incidental royal blues that somehow find their way to a white could "shift" its blue to some other spectral emission but w/ lenses and the narrow beam angles of LEd's certainly not in any major way..

for all intents and purposes a T5 that does not have any phosphors added..

Light is light.. but it is still complicated..

 

[Stolireef]

Thanks for the explanation. So, I guess I'm still a little confused. I assume that different wavelengths of light won't interfere with each other but do they combine to create different colors?

Interesting that you posted a 6500K graph. I think most reef keepers would see that as too warm. Are you saying that it's closest to daylight?

 

[jda]

A par meter measures the quantity of light in a hobby grade, rough manner. You need an integrated sphere to accurately measure output - there are some posts on here about integrated sphere output. As we all know, quality is only half of the battle. The quality or spectrum of what we see are also measured with crude tools that round and smooth lines - some manufactures even lie about their spectrum or blend the edges to make them look better (this happens with all lighting types). It takes like a 100K machine to accurately measure the output. Basically, what I am saying is the spectrum graphs and PAR readings that we have are pretty bad.

I have a college roommate that works at Phillips. He is an engineer on some restaurant and accent LED lighting - which is hard enough he says. His whole explanation is that LED is only efficient because it cuts spectrum. If you want to add the spectrum back in, then they will take the same amount of energy to produce the same output as any other light form - there is no way to cheat the physics. The only thing that he knows about reefs is feeding my fish in college when I was away, BTW - this was just general talk about general lighting.

Saying that light is light or a photon is a photon is like saying a galaxy is a galaxy or a brain is a brain or a reef is a reef. Surely we all know that a reef is a reef and the noobie who just put water in their tank is just like Copps. Right? This is a too simple answer to a complicated question and I don't think that it does anybody any good to say a photon is a photon or light is light. Is there anybody on this board that can rationally and reasonably explain the depth and breath of a quantum that is in the photon? I don't mean James Bond Quantum, either. Rather than talking about quantums and photons being equal, I think that Ron is more on track - spectrum and spread are a huge deal. This is still a complicated thing to figure out when clearly there are differences.

I am amazed that nobody has created at 360 LED that can be reflected - maybe one that just screws into a MH reflector. I would love to know why if anybody does indeed know. I asked at MACNA last year and did not get any good answers.

BTW - You have to take Oreo for what he is. He does not appear to have a tank or reef (never responded to requests on many posts) and just jumps on to post about lighting with internet links and graphs from other places. The 6.5k thing is meant to help where he is coming from, I think.

 

[theatrus]

Thanks for the explanation. So, I guess I'm still a little confused. I assume that different wavelengths of light won't interfere with each other but do they combine to create different colors?

"Color" is something humans perceive (and animals with more than one type of photo receptor, for example bees and some birds can see into the ultraviolet, a fourth type of photoreceptor in their eyes). Energy at different wavelengths doesn't combine to produce a third wavelength on the macro scale.

Humans are sensitive to an area of "blue" wavelengths, "red" wavelengths and "green" wavelengths. "Mixed" colors for us is the ratio of how much of each area of the spectrum we are receiving in our eye - a light could be "yellow" but actually have zero of that spectrum in the above linked charts, but our brain "fills in" the gaps for light its not very sensitive to.

Interesting that you posted a 6500K graph. I think most reef keepers would see that as too warm. Are you saying that it's closest to daylight?

The standard for "daylight" is 6500k in most color systems. Again, daylight doesn't mean "exactly the same as the sun" - the standard is based on the ratio of three primary (RGB) colors.

 

[oreo57]

Thanks for the explanation. So, I guess I'm still a little confused. I assume that different wavelengths of light won't interfere with each other but do they combine to create different colors?

Hmmm well yes.. RGB "combine" to be perceived as "white"..
but I guess you could say it is more of a trick.. "You" see it as white.. It is still RGB..
Blue and red combine to "look" magenta..ect.. Basic color wheel stuff..

Interesting that you posted a 6500K graph. I think most reef keepers would see that as too warm. Are you saying that it's closest to daylight?

Just picked a MH that looked pretty.. but "daylight" can be anything from 3000-10000k (blue sky):

https://www.led-professional.com/re...ent-pigmented-glazes-by-light-spectrum-glazes

you can "tone" the white in any number of ways......but there are never any "new" wavelengths produced..
The sun is "yellow".. Surface of the sun is 5800K-ish...
Interactions w/ various "things" that absorb/transmit "colors" is what your eye sees.
Moonlight is 4000k-ish but doesn't "look" it because of human physiology. It is a "trick"..

the preferred "blue" of reef lighting is part choice, part function.. Hard to say where the line is..
The part about "how" phosphors take one photon and make it another "color" is really even more beyond a needed discussion as my color of stars above..
BUT that is where one truely takes one "color" photon and produces one of a different "color"...

 

[Ron Reefman]

Thanks for the explanation. So, I guess I'm still a little confused. I assume that different wavelengths of light won't interfere with each other but do they combine to create different colors?

Interesting that you posted a 6500K graph. I think most reef keepers would see that as too warm. Are you saying that it's closest to daylight?

The waves of photos don't combine and they do not merge. But we take in all the different wavelengths and the combine them inside or eyes and brain to become different colors. So the light from a red, green and blue spotlights all shine on the same spot on a stage. They are all still red, green and blue when they reflect off the stage and get to our eyes. But then, because they all reach our eyes and brains at the same time, our brain merges them together and we see white. Other animals with different eyes and brains may see very different colors than we do. It isn't the light that changes when mixed together, it's the way we perceive them.

Think of it this way. You mentioned mixing paint. OK, lets say you take equal parts of red, green and blue paint. But these paints can't react with each other to blend. We can break them up into very tiny particles, but those particles remain red, green and blue. If you look at them with a microscope there are red, green and blue dots all mixed together. But when you look at them from a foot away they have blended together (in your eyes) to look white. Does that help at all?

And yes 6500K is the average color temperature of daylight. And yes, most reefers would say that's too warm for a reef tank. But that is because that warm white light has to pass through water to get to the coral. The more water it has to pass through, the more spectrum of light get blocked. Red first, then orange, yellow, green and finally blue. Go down 50 feet as a scuba diver and everything is almost black, white and shades of gray. So most corals in 5' to 30' of water see more cool white (more blue in the mix) and that's what they want from our aquarium fixtures, not daylight 6500K. Here is a chart that shows how far various spectrum penetrate into saltwater.

 

[oreo57]

all colors are present at 3 feet (close to daylight). most are present at 15feet minus UV, IR and most red..
The blue centric/high k white w/ violet (excluding UV which is more of a a "decorative color) is nowhere close to "natural" until you hit about 30ft ...

 

[Stolireef]

Thanks so much to everyone for your responses. I feel like I learned something today.

So, without turning this into a 'which is better thread', does MH or T5 provide a wider variety of wavelengths than LED or are they similarly limited by the phosphors used in the bulbs?

 

[oreo57]

You need to consider individual "bulbs" more than type.
That said Led's are more restrictive at the "tails" in general (cyan range an exception) . More important on the violet end.

 

[jda]

The guys at PS said that they could test good amounts of IR and UV at 10 feet of depth - you are going to get different answers on this with each study that you find, but nobody seems to say more than 12 feet. This does not matter much to us since next to nobody has a tank that is more than three feet deep, so IR from sources that emit it will get into our tanks. However, I find it especially interesting that some well-known shallow water SPS refuse to grow under nearly all LED, but do fine under other types of light and I wonder if IR is important to some organisms - no science, just wondering. Before you laugh, just remember that you might have also laughed when somebody suggested that UV was important only to find out that this is true.

The short answer is yes - MH and T5 provide a wider variety of wavelengths. One of the most important is real UV (not 410 and 420 that LED manufacturers call UV). Some coral - especially some acropora - use it at 380, for example, and spit it back out at lower energy at say 410 which we can see. The UV output is not measured by most PAR meters - just 400-700 - and adds a large amount of energy. Another widely heralded bulb, the T12 Super Actinic VHO, also has a large band if UV and most corals respond very well to it.

 

[oreo57]

However, I find it especially interesting that some well-known shallow water SPS refuse to grow under nearly all LED, but do fine under other types of light and I wonder if IR is important to some organisms - no science, just wondering. Before you laugh, just remember that you might have also laughed when somebody suggested that UV was important only to find out that this is true.

more of a question .. how many ran Daylight balanced LED's for these tough to grow ones? Maybe just needs more red not IR or UV..

LEDs and Acropora...Please shed some light on this topic (urrghhhh...)

Good topic Scott and one I've been immersed in a while now myself. And with incredible results. Been saying it for a little while now, but I really believe the secret is in the warm/neutral whites. I ran fixtures with cools and warms over the same system and the results were very clearly discernable as to what worked and what didn't....Not going for the plug here but to illustrate my convictions, everything in this pack but the purple guy was grown 100% under LEDs. I could show you many many more. Color's there and so is growth. For me the question as to "do they?" has long been answered. It's now more a question of "for how long?"

Pretty sure I can't post the link..

 

[jda]

I wish that I knew what was missing. This is a little bit of a catch 22 because the people who succeed with these kinds of corals well into colony sizes will not use LEDs. ...and the LED people who try and keep them and fail will absolutely not blame the lights since everybody told them that they are equal (and we as humans tend to defend our purchases) and it is usually an alk issue or phosphate problem, etc.

For the upper part of the spectrum, it could be red, but fixtures like the AcroOptics and Hyperion are full of red and they aren't any different as far as results... a small sample size for sure.

I am pretty sure that UV is a big deal. Most of the people who have added T5 use blue bulbs and the true UV (under 400) is the thing that stands out the most there. Are there any fixtures with true UV? I know that manufactures misrepresent (lie) and say that their 410 and 420 chips are UV, but I mean real UV?

Ignoring that there is a difference does not help development and innovation. I would like to see more people acknowledge that there are real differences and not just say that "each can grow coral." To say that they can produce the same results is dangerous not only for the buyer but for the innovators since they can get complacent without lack of sales to drive them. There has not been much since multi-spectrum chips replaced the white/blue.

 

[oreo57]

It's no secret that Unique Corals grows tons of Acropora. We are near-obsessed by Acros, especially Millies, Vermiculata, Tenuis, etc. We grow them under 400 watt, 20,000K "Radium" metal halides on light movers. Those of you who have been to our facility or who have ordered from us know that our Acros are pretty darned nice (if I say so myself...).

to be honest, it is not very "special" as to spectrum..

 

[karimwassef]

I used dedicated 3W 365nm UV LEDs and it did change the real color of my corals (like tanning). They also made them glow when no other lights were on, but that's a temporary effect of being under UV.

I don't know if they caused the corals to grow faster.

 

[Stolireef]

I guess I'm about to add to the experiment. I just mounted a pair of Gen 4 Radions over my new build 110 rimless. The entire build is designed to keep SPS so I guess we'll see how it does. I have a 2x250 and 2xT5 fixture at the ready if the experiment fails.

 

[oreo57]

I guess I'm about to add to the experiment. I just mounted a pair of Gen 4 Radions over my new build 110 rimless. The entire build is designed to keep SPS so I guess we'll see how it does. I have a 2x250 and 2xT5 fixture at the ready if the experiment fails.

https://www.google.com/url?sa=t&rct...XhPgv5-6MHBwNQ8lg&sig2=ZIDXFOUxnD-WWn9Ogs712w

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