It may not be necessary to change MH bulbs yearly

[Ace25]

Okay, but how does that extra efficiency translate into actual usage? Is it appreciable? Is it necessary to go through the trouble?

Other than the very scarce and limited data available I don't think anyone can say how the extra efficiency translates to every coral. I am sure there are slight variations among them all. Is it appreciable... probably not. The last question, is it worth it, here is how I think of it. Each area of reefkeeping is its own puzzle.. lighting, flow, filtration, nutrients.. and on and on.. with lighting for this hobby, the research has led us to complete 90% of the puzzle. While is it one of the most complete puzzles and the remaining 10% probably wouldn't benefit the hobby nearly as much as more research into other areas that need it, I just like to see the puzzle get completed. We have the intensity part down, we just need to get the spectrum down to match the sun at certain depths in the ocean. With LEDs we could even make the lower left corner of the tank a high light area for acros and the top center a low light area for acans with LEDs, couldn't consider that with MHs.

I'm just not convinced, as most of the articles I have read on the subject fall woefully short of a real or even a good conclusion. Yes, corals have a very slight skew toward efficiency with the blue ranges. But why do corals do miserably when there is almost all blue light (the converse is also true), like actinics? Part of the issue is that there aren't enough blue photons available to give a huge advantage to bluer spectral absorption. It takes more energy to output bluer photons than it does other photons, despite the fact that all photons have the same energy (how much of that energy is used is what relates to the efficiency). You can provide more energy in the other spectra due to the fact that these other spectra require less energy to create. That doesn't mean that blue can be omitted outright, as the greatest efficiency peaks will result with application of broad spectra. You get some blue, along with a higher peak in reds, making up for the deficiency in blues .

Good stuff there and your absolutely right.. it takes a lot more energy to get the right amount of blue photons, you would need around 3 actinics to replace 1 10k to equal the output, and you simply can not fit enough actinics by themselves over most tanks and still give it the intensity it requires, as well as what you pointed out, corals need a broad spectrum. I believe we need to mimic the sun.. HPS lights have a better spectrum arc than MH lights but even those have their limitations. I would just like to have the ability to have a starting point of mimicing the suns spectrum and then be able to adjust and skew it to the blue side manually. I want to mimic the exact lighting conditions the corals I have get in the ocean, and if my corals come from 6-8' deep in the water, I want the light I am giving in my tank to be the same spectrum as what it would receive in nature, so I would have to shift my lighting to the blue side since my tank is not 6' deep.

I'd love to see some analysis that looks at the greatest amounts of productivity in corals with different spectra. I have the feeling that broad spectra will beat out both bluer and redder lamps in terms of overall productivity. You can look at any absorbance charts and see that the likelihood is high for this. This, coincidentally, is more similar to sunlight in shallow water, which is what these animals evolved to utilize.

Again, completely agree.. need a broad spectrum over focusing mainly on a single one.

That being said, I think a good number of aquarists are reaching the point that there is almost too much light provided. This is happening a lot more than it used to and it is reasonable, assuming the advances in reflectors, maximizing intensity, etc. This would also explain, much more plausibly than a small edge in efficiency of utilization, that bluer lamps or a shift into bluer spectra, in general, are having profound effects. Basically, the overall reduction in intensity is more likely to blame for the increased growth rates, etc. that many experience now.

In any case, PAR is all light that is available in the most common photosynthetic ranges for chlorophyll. Pretty much all photosynthetic organisms will be able to use at least some of the spectra within the ranges of PAR--corals and plants are no exception. Yes, some of the absorbances will be slightly different (mainly due to accessory pigments, etc.), even between closely-related species, but the overall range is pretty standard across the board, which is what makes it such a useful measure.

Edit: In all, while I always support further research into anything, I think that aquarists overthinking the findings and applying them outside of their contexts. Not purposely, mind you, but I think it is fueling a good deal of misconceptions (and the consequent head-banging, hair-pulling quandaries that often pop up). I think we've arrived at a point where lighting is as efficient and efficacious as it needs to be in terms of providing the maximum intensity necessary (and then some), honestly. Sure, new ways of providing that will pop up, but I don't see any huge advances in terms of providing actual light making that much of a difference. I think there are more areas that could be of even greater benefit to the knowledge pool for coral husbandry (deeper understanding of individual species' actual lighting needs, nutritional requirements, foods, etc. seem a likely candidates). JMHO.

Yup, I agree.. we are getting to the point of providing too much intensity of light and the coming advances in lighting will not be nearly as big or groundbreaking as advances in other areas you mentioned. As far as "is it efficient enough".. well, it is to keep corals alive.. but that is like Ford saying "we built the model A, it is more efficient than the model T, don't need to research anymore into more efficient engines because these will get us from point A to B just fine". While safety systems were needed much more than more efficient engines on those cars, it doesn't mean stop working on more efficient engines all together.

 

[Ace25]

Great article by Sanjay Joshi about the sun vs mh lighting and spectral differences.

http://www.advancedaquarist.com/2005/8/aafeature

 

[Amphiprion]

Sure it will vary between corals. That's part of why I question it. Maybe by making tanks bluer, we are only favoring an exceptionally narrow slice of the pie, so to speak. We may only be catering to a fraction of the corals we want to keep.

Sanjay has always done top-notch work. He's been one of the best, if not the best, source of lighting info in the hobby from a physical standpoint.

 

[Ace25]

Sure it will vary between corals. That's part of why I question it. Maybe by making tanks bluer, we are only favoring an exceptionally narrow slice of the pie, so to speak. We may only be catering to a fraction of the corals we want to keep.

Sanjay has always done top-notch work. He's been one of the best, if not the best, source of lighting info in the hobby from a physical standpoint.

Not going to disagree because my thoughts are just "theories" so to speak with limited data to back it up so I am not about to stand on a soap box and say my thinking is the correct way and everyone must listen, quite the opposite actually. I just want to put out how I think about lighting and let others decide if they want to use any of it in their lighting setup.

That said, when I look at charts like this one and see that red photons lose 90% of their intensity at only 3ft of water and I personally believe most of our corals we keep are at depths around or deeper than 3 feet in the ocean that tells me they are relying a lot on the blue side of the light spectrum since the red side gets filtered out so quickly.

Sure, if we all had tanks full of pocillopra corals, which are known to grow right at surface levels of the ocean most of the time, then full spectrum lighting would be better than a blue shifted light. I just think the majority of corals we keep are adjusted and better suited to utilize the blue side over the red side so when the blue side of a MH burns out quicker than the red side I feel you are losing a good part of your "quality" lighting but still keeping most of the "quantity" of light.

Again, these are JMO and I have no issues with anyone disagreeing with me because this is just something I believe is true, but since I have to hard data to prove without a doubt my thoughts I won't get upset in the least if others disagree with me.

Edit: I want to make clear I am not advocating a "blue lit tank", I am simply saying I believe lighting needs to be slightly shifted to give out more blue light to compensate for the lack of depth of aquariums as well as the fact the blue part of light bulbs burn out much quicker than the red part. You still need the FULL spectrum of lighting for corals. I do not believe if you do or don't do this will mean the survival or death of corals.. I just think corals will do slightly better under a blue shifted tank. Like Amph mentioned, other areas of research would play a bigger role in coral health than fine tuning the lighting.. but lighting part of the hobby it what interest me more than other areas and I would just like to see the lighting puzzle completed.

 

[Amphiprion]

I'm not necessarily advocating 6500K lighted tanks, either. I think 10K-12K is a good starting point, myself--if anything, for aesthetic reasons. We've known that water filters down lower frequency light waves for years, which is what contributes to making water look blue. Corals at any appreciable depth have adapted to that fact. That being said, many corals, even within the same species, will be so variable to this that it is difficult to say anything across the board. If you've seen Acropora beds in back reefs mere inches below the surface, you can see what I mean. You can find that same species yards away in a much deeper area. I guess the takeaway message is that unless we know the individual circumstances of each coral, it is difficult to say if one may be better than the other. Even then, given the adaptability and plasticity of corals in respect to lighting, is it worth the extra effort? If you like the look, I think so. If not, I don't know if it can be justified. If you are energy-minded, bluer lighting (like 20K) may not be the best choice. It boils down, quite a bit, to individual preference. One thing is certain, however, in that intensity is definitely a necessity. Blue, full spectrum, red, or otherwise. Without that, there isn't much any of them can do, which brings back full circle to PAR.

As far as "is it efficient enough".. well, it is to keep corals alive.. but that is like Ford saying "we built the model A, it is more efficient than the model T, don't need to research anymore into more efficient engines because these will get us from point A to B just fine". While safety systems were needed much more than more efficient engines on those cars, it doesn't mean stop working on more efficient engines all together.

That's why I included that part earlier, mainly as a subtle reference to LED lamps--i.e. providing new ways to achieve the same thing. I don't think we should stop developing new kinds of lighting, I just don't think we need to try to completely re-invent the wheel in terms of lighting for corals in general. We've already reached the point where lighting is sufficient and in many cases, more than sufficient. It's a matter of providing that in different, more energy-efficient ways (and more sunlight-like) that will still be continuing.

 

[Ace25]

LOL.. so.. going back full circle and back to PAR, with all that has been discussed, is PAR a good measurement for bulb life? Unless your using PAR readings from the bottom of your tank, which actually come to think of it, may be an excellent way to judge bulb life in my little world, I don't think it is. If you go by the readings at the bottom you will see how the blue spectrum burns out with age and when it reaches a certain point you will know it is time to replace it. Measuring at the surface/air is the wrong way to measure for bulb life using PAR.

As you pointed out Amphiprion, spectrum is a minor and intensity is a major factor. So, since intensity matters most, how would corals placed lower in the tank that may be close to the lower limits of acceptable PAR levels react when the bulbs start to go bad?

Here is a good example. The Sunset Montipora has a VERY broad range of acceptable PAR levels that I have found. I have personally seen it grow just as good under 300 PAR as 2000 PAR. I personally think the coral looks much better with the Sun as its main lighting + actinics for supplements vs a 14k/20k MH light. The colors are much richer and more vibrant when grown under SolaTubes. That being said, it also does not live well PAR readings lower that 250 from what I have witnessed. So if you place this coral lower in your tank where say it gets a 400 PAR reading on a new bulb, as the bulb ages that reading will drop to 300 or below and the coral will then suffer from lack of intensity, but the intensity is from the blue spectrum. So while yes, the blue spectrum doesn't play that big of a role in PAR readings at the surface of the tank, as you go deeper into your tank it plays more of a role. I just wanted to stress just how little water it takes for intensity to really drop off from the red being filtered by the water.

I have a PAR meter and a camera if anyone wants me to take pics of anything to show readings at different spots in my tank and I tank take pics with different MH bulbs and different T5 bulb combinations.

 

[dolfans1]

Since Red photons move much faster than blue photons, at a rate of close to 3:1 I believe, that means the PAR reading off the bat is going to give you a skewed reading that leans to the red side already, since 3 red hit the sensor for every blue even though blue is utilized more efficiently.

Not sure what you mean here. All light at every wavelength from radio up to gamma rays travels at exactly the same speed - 3.0 x 10E8 m/s in a vacuum, slower in air, and slower still in water. A good photometer should give an equivalent reading no matter the wavelength. What can affect the reading is the sensitivity of the actual meter to different wavelengths.

It takes more energy to output bluer photons than it does other photons, despite the fact that all photons have the same energy (how much of that energy is used is what relates to the efficiency).

Hate to nitpick, but the energy of a photon is directly related to the wavelength by the equation E=hc/l, where h is Planck's constant, c is the speed of light, and l is the wavelength. Blue and violet light, which has the shortest wavelength in the visible, has higher energy then red and orange. This is what enables blue light to penetrate further into water than red.

I would think that we should be able to get some idea of coral's spectrum requirements from their colors. Corals that are predominantly green in color means the zooxanthellae are absorbing the reds and oranges but reflecting the greens. Corals that are purple are absorbing the yellows and reds but reflecting the purples and blues. A lot of corals are multicolored, and while we think of them as being nice to look at, the colors are most likely a reaction to the available light spectrum and the coral's requirements.

 

[Ace25]

I knew someone would call me on the "speed" thing. I knew that wasn't the right terminology to use but I was hoping people would understand what I meant.. I meant to say it takes 3x the energy (very rough estimate) to create the same amount of blue than it does red. Looking back I am going "Doh!, why did I say it that way" after rereading it. Thank for pointing that out and correcting me.

Just for information, here is a picture of light wavelengths for people to look at.

Light is made up of waves. Some waves have different sizes. The distance between the top of one wave and the top of the next wave is called the "wavelength". Different colors of light have different wavelengths. Red light has long waves. Purple light has short waves. Green light is in between. The wavelength of green light is around 550 nanometers (nm). This is the same as 5,500 Ångströms (Å). Light with short waves has more energy than light with long waves. Purple light has more energy than red light.

Think of light as one of those Ultrasonic toothbrushes.. the cheap $5 crest battery powered ones move very slow and don't do much vibrating meaning not much cleaning... then take a $100 Oral-B ultrasonic toothbrush and compare it.. it will vibrate right through the resistance and get through the junk. That is how I think of light waves.. red is slow and can't vibrate its way through the density of the water where as the blue vibrates very fast and can penetrate easily.

 

[Amphiprion]

Hate to nitpick, but the energy of a photon is directly related to the wavelength by the equation E=hc/l, where h is Planck's constant, c is the speed of light, and l is the wavelength. Blue and violet light, which has the shortest wavelength in the visible, has higher energy then red and orange. This is what enables blue light to penetrate further into water than red.

Good eye, and that is entirely true of the physical properties of light. However, biologically speaking, this isn't true of the energy provided in photosynthesis by a photon. One photon equals one electron in the photosystems within a chloroplast. Therefore, a photon is a photon in terms of photosynthesis. It's just with at least some corals, there is a very minor degree of efficiency in harvesting the overall energy from the photon due to many specialized accessory pigments. That extra energy can collect into more electrons sent down the chain. I say "can" because I am not sure of the exact mechanism in which this occurs, honestly. I'd have to do some digging.

Edit: a good review of photosynthesis: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html

I would think that we should be able to get some idea of coral's spectrum requirements from their colors. Corals that are predominantly green in color means the zooxanthellae are absorbing the reds and oranges but reflecting the greens. Corals that are purple are absorbing the yellows and reds but reflecting the purples and blues. A lot of corals are multicolored, and while we think of them as being nice to look at, the colors are most likely a reaction to the available light spectrum and the coral's requirements.

Again, not a bad assumption at all--very logical, in fact based on the physical properties of light. However, we are dealing with zooxanthellae in terms of the actual point of photosynthesis, not necessarily the coral colors. Zooxanthellae, like all photosynthetic organisms, show peaks in red and blue absorbance. Again, they seem to be slightly better at collecting blue light compared to other organisms. Also, many of the colors you see on the actual coral are not simple re-emitted colors, but fluoresced colors.