taking a break from LED

[inverted]

I don't think it's as much UV as it is some peak in the 420 nm spectrum, that's what many generally believe to be true. If you look at the peak for most LED units--including the higher end ones, they peak at around 430-450nm. It's believed that the best spectrum for coral is in the 420nm wavelength. Actinics generally peak in the 420nm, so if you supp your LED's with T5 actinics, that should be the best combo based on present belief.

Yeah, people keep saying "we don't know" people on internet forums may not know, but there is actually a lot of research. So, there is certainly things we don't know, but "we know" more than most people seem to think.

Here is some good info on uv "Playing with Poison"
http://www.advancedaquarist.com/2004/8/aafeature

Danna also has written probably around 20 or so articles, summarizing scientific research, as well as his own research, on coral coloration and color pigmentation. I am not going to link all of them, but here is the first of one of his series. You can search further if interested.
http://www.advancedaquarist.com/2009/1/aafeature1

This is a topic that really has been surprisingly well studied, it just doesn't seem to make it to the hobby. For whatever reason, hobbyists seem determined to reinvent the wheel sort of speak. Perhaps much of it is just too technical. The jist of it though is coral coloration is a response to high intensity blue light, generally in the 400-500ish nm range. Also note, pigments can either reflect light, or fluoresce i.e. absorb light and emit light of a different color. If you reflect UV light, the reflected light will be invisible, as we humans can not see uv. All pigments found so far to respond specifically to UV (i.e MMAs) are reflective pigments and therefore not visible. There is one slight exception, realized within the last few years, this is Green Fluorescent Protein GFP. GFP, takes high energy light and reduces the energy by absorbing some energy and re-transmitting at a different wavelength. However, it isn't specific to UV, it responds just as well to high intensity blue light.

 

[dz6t]

Inverted, are you just back from a vacation or something? Have not seen you post for a long time.

 

[inverted]

Inverted, are you just back from a vacation or something? Have not seen you post for a long time.

I'm like the guy in the Allstate commercials and just decided it was time to add some mayhem to your thread

Nah, I had some redbugs, then once the tank was recovering, had a controller failure and semi-crash. Plus a busy summer, so, I took a bit of a hiatus. I don't know if anyone told you, but it can be a frustrating hobby.

 

[newenglandreef]

Yeah, people keep saying "we don't know" people on internet forums may not know, but there is actually a lot of research. So, there is certainly things we don't know, but "we know" more than most people seem to think.

Here is some good info on uv "Playing with Poison"
http://www.advancedaquarist.com/2004/8/aafeature

Danna also has written probably around 20 or so articles, summarizing scientific research, as well as his own research, on coral coloration and color pigmentation. I am not going to link all of them, but here is the first of one of his series. You can search further if interested.
http://www.advancedaquarist.com/2009/1/aafeature1

This is a topic that really has been surprisingly well studied, it just doesn't seem to make it to the hobby. For whatever reason, hobbyists seem determined to reinvent the wheel sort of speak. Perhaps much of it is just too technical. The jist of it though is coral coloration is a response to high intensity blue light, generally in the 400-500ish nm range. Also note, pigments can either reflect light, or fluoresce i.e. absorb light and emit light of a different color. If you reflect UV light, the reflected light will be invisible, as we humans can not see uv. All pigments found so far to respond specifically to UV (i.e MMAs) are reflective pigments and therefore not visible. There is one slight exception, realized within the last few years, this is Green Fluorescent Protein GFP. GFP, takes high energy light and reduces the energy by absorbing some energy and re-transmitting at a different wavelength. However, it isn't specific to UV, it responds just as well to high intensity blue light.

The problem is that there is research, but because there are so many factors that actually affect coral coloration, the jury is still out on the cause and effect equation. Many say that, when they switched to/from MH and T5, colors faded and took a very long time to re-acclimate to the new light and regain their colors. Many believe this to be the same issue with the changeover to LED's--that, because of the drastic change in spectrum, corals will temporarily dull or brown out. Also, the PUR per PAR of LED's are significantly higher than MH/T5. So, while many say that the 420nm is beneficial and lacking in the LED's, there's no real evidence that it's actually the issue causing dulling (or with UV). LED's do have 420nm, they just don't peak at 420nm. There is a giant thread on RC where there is general agreement that nobody really knows the issue or why some experience coloration issues with LED's while others do not. But I believe that, with proper intensity and proper supplementation for what lacks in spectrum, you can achieve the same results--with a much, much cooler and energy efficient light source (and plenty of cool features, like sunrise and sunset). Completely agree that LED's are not presently plug and play.

 

[dz6t]

For all these long post, I need a text to speech convertor to get through them. Just kidding. Great information.

 

[dz6t]

With all my halides in the basement, I am getting a sun tan...it is tropical down here and I actually put a beach chair next to the tanks. Feels good in winter.

 

[s_kelley]

Put plants in there like I do they love the light and humidity

 

[frank180reef]

Put plants in there like I do they love the light and humidity

I put my banana trees down there and citrus, they arent as happy (as compared to when I had MH) with the directional LEDs I now have

 

[inverted]

The problem is that there is research, but because there are so many factors that actually affect coral coloration, the jury is still out on the cause and effect equation.

Yeah. Due mostly to interest as markers in molecular biology research, we know an incredible amount about what pigments exist, in what corals even and what light activates them etc... Why that light may or may not be sufficient in one tank or another is tough to say. People aren't exactly doing controlled experiments in their aquariums. That doesn't mean we don't have enough info to make some educated guesses. For example, we know mcav5 responds to 435nm light and Montastrea cavernosa contains mcav5. Now lets say we have a Montastrea cavernosa and it is dull. Do we have 435nm light, maybe we just have "blue" LEDs. So, no, so, that would explain it. However, now we add some LEDs with 435nm emission, does the coral improve. No? So what else could be going on? We don't know. We can make some guesses though. We know stress and/or lack of nutrition can effect coral color. Corals symbiotic algae mostly produces carbohydrates and especially in lower nutrient environments don't necessarily produce sufficient nutrition, such as amino acids for the coral, largely just energy. So, corals need to eat too. We also know food sources, in our aquariums are generally sparse compared to the ocean and some people do report feeding or supplementing amino acids help. Other times it doesn't. So, what then?

We know that under high irradiance, corals symbionts produce lots of O2 and need water movement to break down the membrane barrier layer and allow gas exchange. So, is there good flow? We also know metals can react with coral pigments and deactivate them and salts due to impurities in the manufacturing process and foods, due to bioaccumulation, contain lots of metals. Metals can bind to proteins and be removed via GAC, also, GFO is extremely good at removing metals, as are specialty products such as cuprisorb. So, are these being used? etc... We know some things about coral polyp extension too, we know some corals extend polyps to help increase surface area for gas exchange, under intense illumination. We also know other corals extend polyps, especially those with high zooxanthellae counts in the polyps, can extend polyps to increase surface area for illumination. So, was there a change in PE when switching lights, perhaps this indicates a change in PUR.

For sure though, we can't exactly say what causes or doesn't cause some tanks to have different responses to lights, but we certainly know a lot about what the causes could be. Many causes have to do with corals demand from the environment, given different light schemes, for example, in other words, these have to do with interactions between light and other environmental factors. If we consider this broader schema and avoid the tunnel vision of many forum threads seem to fall back too i.e. "uv" or "lack of spectrum" etc.. I think we as a hobby would be better off. Not that everyone wants to think about such things LOL. Some people definitely should wait for more plug and play LEDs, or confine LEDs to experimental tanks, until they have built some intuition.

 

[inverted]

With all my halides in the basement, I am getting a sun tan...it is tropical down here and I actually put a beach chair next to the tanks. Feels good in winter.

Sounds good to me, break out the Coronas and an extra chair and I'll be right over!

 

[dz6t]

Put plants in there like I do they love the light and humidity

My basement is actually very dry. I don't know why.

 

[newenglandreef]

If we consider this broader schema and avoid the tunnel vision of many forum threads seem to fall back too i.e. "uv" or "lack of spectrum" etc.. I think we as a hobby would be better off. Not that everyone wants to think about such things LOL. Some people definitely should wait for more plug and play LEDs, or confine LEDs to experimental tanks, until they have built some intuition.

Very true and well said. I do believe LED's are here to stay. It's an excellent light source in my view. The tough part is all the time it takes for corals to respond to changes (well, at least positive changes) and the varying length of time they take to respond. Dime-ing in a cal reactor was hard enough when I could directly test for them. With nothing to test (including with a typical PAR meter, which doesn't accurately measure LED's), it's very difficult to get these correct. Very little immediate feedback. Going to take some time for sure.

 

[newenglandreef]

I put my banana trees down there and citrus, they arent as happy (as compared to when I had MH) with the directional LEDs I now have

Frank are you switched over to all LED's now?

 

[Pat02026]

How would I go about measuring the spectral output of a fully controllable led fixture, assuming it is capable of reproducing what I'm after of course, to replicate the par and color (forgive my lack of proper description/terminology) of my 250w pheonix 14k which my corals and eyes love? Obviously par meter for par, but what about spectrum and or other properties that are comparable? Or is this the million dollar question

 

[dz6t]

How would I go about measuring the spectral output of a fully controllable led fixture, assuming it is capable of reproducing what I'm after of course, to replicate the par and color (forgive my lack of proper description/terminology) of my 250w pheonix 14k which my corals and eyes love? Obviously par meter for par, but what about spectrum and or other properties that are comparable? Or is this the million dollar question

There are published spectrum for some LED lights, but, they are "smooothed".
True continuous spectrum LED are very expensive. They are mainly used for medical devices that require high CRI.
So don't expect any current LED has this fancy thing in it.

 

[newenglandreef]

How would I go about measuring the spectral output of a fully controllable led fixture, assuming it is capable of reproducing what I'm after of course, to replicate the par and color (forgive my lack of proper description/terminology) of my 250w pheonix 14k which my corals and eyes love? Obviously par meter for par, but what about spectrum and or other properties that are comparable? Or is this the million dollar question

That's the million dollar question. With some LED's (like Radions), you can actually set the light for the exact look you want (like a 14K look). I've read up on RC that people are having a lot of success with a 20K look--so their experience combined with my understanding of blue being in the most useable spectrum for coral, I have a very blue look in my tank for the time being, which I personally like anyway. But even with the blue/white LED's that are dimmable, you can really replicate the look to whatever you want, from 10K to 20K. The effect it's having on corals, however, is a different story. Light sources are definitely not all the same-- so I don't think you'll be able to replicate a MH through a LED. That's not to say LED is worse, just different.

 

[dz6t]

But even with the blue/white LED's that are dimmable, you can really replicate the look to whatever you want, from 10K to 20K. The effect it's having on corals, however, is a different story. Light sources are definitely not all the same-- so I don't think you'll be able to replicate a MH through a LED. That's not to say LED is worse, just different.

Bingo!

What our eyes see is a Perception of light. For example, our eyes can perceive white light with a blend of narrow spectrum of blue, green and red (that is how color TV and monitor work). But this "white" light is not the same as the "white" sunlight we see, which is composed with a continous spectrum.

 

[inverted]

a typical PAR meter, which doesn't accurately measure LED's

A typical PAR meter may measure halides even less accurately though by the way, as examined here: http://www.bostonreefers.org/forums...ion-examined-Lighting-Spectrum-and-HEV-thread

Everyone seems to forget that the meter measures the 400-430nm light put out by a lot of halides, much more inaccurately than the 450nm dominant light of many LEDs. Also people seem to forget the meters don't measure red accurately, which LEDs (with exceptions) don't put out a lot of. Interestingly, for this reason, the XM 10K would be expected to be the most underestimated.

I think you'll never get spectral adjusted PAR unfortunately, but we probably could get energy adjusted PAR. The light that corals seem to respond to most, is high energy blue and violet light. We can easily calculate the amount of energy of a given wavelength. For example, 400nm violet (or "uv" in hobby terms LOL) would be 299 KJ/mol, 450 blue 266 KJ/mol, 239 KJ/mol for 500nm "green", down to a measly 171 kj/mol for 700 nm "red" light. So, a light like the XM 10000K is able to put out a ton of PAR, because it takes less energy, to produce lower energy light, which it has plenty of. Most of this light is probably wasted though on deeper water corals, but may be beneficial to shallow water acros and clams. On the other hand, an XM 20000K, may not have as much PAR, but may still output lots of energy in the "PAR" (or just "visible") spectrum. This may be more useful to many deep water corals, but may be lacking for some shallow water acros and clams etc... The same principles apply to LEDs. Personally, I think averaging the published spectral curves, over energy levels, to provide energy output, as well as PAR, would be a useful metric. This would help determine the true light output and efficiency of the light. Of course looking at the spectral curves is good to, but is tough it becomes tough to make quantitative comparisons.

 

[newenglandreef]

Bingo!

What our eyes see is a Perception of light. For example, our eyes can perceive white light with a blend of narrow spectrum of blue, green and red (that is how color TV and monitor work). But this "white" light is not the same as the "white" sunlight we see, which is composed with a continous spectrum.

And it gets even more confusing when corals are submerged in 60+ feet of ocean, where mostly only greens and blues reach, visibly.

 

[inverted]

so I don't think you'll be able to replicate a MH through a LED. That's not to say LED is worse, just different.

I don't completely agree, it depends on the halide. A Phoenix 14000K for example, is pretty darn similar to some RBs with some neutral whites mixed in. However, good luck trying to match an Ushio 14000K, or an XM 10000K for example. Although, I remember once seeing some work on some Japanese forums, that did get close.

As to Pats question, you can look at published spectral curves, such as on Sanjays reef lighting guide on the manhatan reefs website and look at manufactures data to get a good idea. The problem with manufactures data though, is it is scaled to human vision perception i.e. lumens not total magnitude (more or less PAR). So, technically, mathematically it is easy to combine spectral curves and estimate the combined spectrum, but to be really accurate you need know the scale/ i.e. total output and magnitude which isn't always available. Luckily with LEDs the total output, for a given wattage is generally pretty close, so you can guesstimate, but still only so accurately....