PAR? Important Right? But......

[neuwave]

Hi guys, as you all well know everyone is looking for more par in leds. Post after post I hear the people fighting about who has the most par, either leds, mh, compacts, t5's, etc.

 

But not one person have discussed the light that is actually being emitted.

PAR - Photosynthetically active radiation. From what I remember it measures from 400 nanomaters to 700 in light wave length. Which allows photsynthetic animals to harness the light and convert into sugars/food for the host coral or plant. As for plants this is perfect, light traveling from the sun to the earth were par is normally measured. But our prized corals have anther layer of salt water above them that alters and reduces the spectrum/light waves reaching them. Yes, I know some corals do breach the surface at low tide but that is besides the point.

 

A while back I used to email evil about the hunt for the 420 nm (purply in color) wavelength led, but my search brought up some weird finds. Unfortunaley I didn't find any high powered or a true 420 led. This wavelength does help in the coral photosynthesis. Are the chlorophyll-A, chlorophyll-B, and carotenoids and such recieving the correct light? Why are we putting par on the on such a high pedastall rather than the quality of light being recieved on the corals. Then up the par of the correct wavelength.

 

When I went to macna alot of the led vendors were so hyped up on the amount of par they could put out. But they mostly used white to up their par. That's great for plants but for corals? hmmm, just raises an eyebrow. Alot of the leds sold today have a 6500k temp to them and then we add blue to add extra spectrum. It seems like the new fixtures are using alot of white for the par crazy people, which looses the quality of the light actually feeding the corals.

It seems to be a whole quanity over quality situation. Even the flood lights at the hardware store have great par readings, but its not the kind of light that corals need to grow well.

 

So does the par we are getting a true value of what spectrum of light corals need? Are we being sold a cruise ship with just a sail? Looks flashy but it looks like we'll be arriving in Hawaii in 2 to 4 years.

 

This has been bugging me for a while so any input would be great thanks for reading.

[Adam_T]

Hi guys, as you all well know everyone is looking for more par in leds. Post after post I hear the people fighting about who has the most par, either leds, mh, compacts, t5's, etc.

 

But not one person have discussed the light that is actually being emitted.

PAR - Photosynthetically active radiation. From what I remember it measures from 400 nanomaters to 700 in light wave length. Which allows photsynthetic animals to harness the light and convert into sugars/food for the host coral or plant. As for plants this is perfect, light traveling from the sun to the earth were par is normally measured. But our prized corals have anther layer of salt water above them that alters and reduces the spectrum/light waves reaching them. Yes, I know some corals do breach the surface at low tide but that is besides the point.

 

A while back I used to email evil about the hunt for the 420 nm (purply in color) wavelength led, but my search brought up some weird finds. Unfortunaley I didn't find any high powered or a true 420 led. This wavelength does help in the coral photosynthesis. Are the chlorophyll-A, chlorophyll-B, and carotenoids and such recieving the correct light? Why are we putting par on the on such a high pedastall rather than the quality of light being recieved on the corals. Then up the par of the correct wavelength.

 

When I went to macna alot of the led vendors were so hyped up on the amount of par they could put out. But they mostly used white to up their par. That's great for plants but for corals? hmmm, just raises an eyebrow. Alot of the leds sold today have a 6500k temp to them and then we add blue to add extra spectrum. It seems like the new fixtures are using alot of white for the par crazy people, which looses the quality of the light actually feeding the corals.

It seems to be a whole quanity over quality situation. Even the flood lights at the hardware store have great par readings, but its not the kind of light that corals need to grow well.

 

So does the par we are getting a true value of what spectrum of light corals need? Are we being sold a cruise ship with just a sail? Looks flashy but it looks like we'll be arriving in Hawaii in 2 to 4 years.

 

This has been bugging me for a while so any input would be great thanks for reading.

 

 

I have a DIY 24 Cree LED system over my 34 gallon cube and I have awesome PAR numbers and my corals are loving the light....I've never seen them grow so quickly!

[neuwave]

Lol I I have a diy led too. I honestly think the diy people have better spectrum than the ones sold at the store. Because we can vary and dim the amount of light given to our corals. I really like LEDs but the non diy systems seem to put too much emphasis on par rather than spectrum quality and volume.

[blasterman]

Post after post I hear the people fighting about who has the most par, either leds, mh, compacts, t5's, etc.

 

Anytime you have a technical DIY environment that has a demographic of mostly males in their 20's you'll have benchmark wars. Simply browse through any DIY computer forum and watch the Intel and AMD geeks go at it like Sunni's and Shia's and slinging synthetic benchmark numbers around like loaded guns. In DIY LED forums it's the same mentality.

 

Several years ago PAR wasn't even mentioned on reefing sites, but now with DIY LEDs it's a big issue, and annoying. Fluorescent and halide guys have always gone at each other, but PAR wars were never like this. The sad thing is most people don't even know what their PAR meter is measuring given most (not all) aren't calibrated for the spectral requirements between tomato plants and acropora. Anybody tried reading the PAR of a HPS (high pressure sodium) light and then tried to grow acropora with it? My point proven.

 

I'm not a biologist, but I still believe that most of the action spectrum for corals is above 440nm and tapers off somewhere less than 500nm. Does this mean both Clorophyll A+B are present? Dunno....seen white papers claim one and then the other. I do know that there is very little energy below 440nm with LED lights, and yet nobody is having problems growing SPS with them. This would seem to exclude the need for 420nm light for coral growth. However, this doesn't mean it accomplishes other pigmentation things.

 

If colors warmer than blue accomplish anything in corals I haven't seen much evidence of it, but there's been little research done on it.

[Amphiprion1]

Anytime you have a technical DIY environment that has a demographic of mostly males in their 20's you'll have benchmark wars. Simply browse through any DIY computer forum and watch the Intel and AMD geeks go at it like Sunni's and Shia's and slinging synthetic benchmark numbers around like loaded guns. In DIY LED forums it's the same mentality.

 

Several years ago PAR wasn't even mentioned on reefing sites, but now with DIY LEDs it's a big issue, and annoying. Fluorescent and halide guys have always gone at each other, but PAR wars were never like this. The sad thing is most people don't even know what their PAR meter is measuring given most (not all) aren't calibrated for the spectral requirements between tomato plants and acropora. Anybody tried reading the PAR of a HPS (high pressure sodium) light and then tried to grow acropora with it? My point proven.

 

I'm not a biologist, but I still believe that most of the action spectrum for corals is above 440nm and tapers off somewhere less than 500nm. Does this mean both Clorophyll A+B are present? Dunno....seen white papers claim one and then the other. I do know that there is very little energy below 440nm with LED lights, and yet nobody is having problems growing SPS with them. This would seem to exclude the need for 420nm light for coral growth. However, this doesn't mean it accomplishes other pigmentation things.

 

If colors warmer than blue accomplish anything in corals I haven't seen much evidence of it, but there's been little research done on it.

 

Both forms of chlorophyll will be present in zooxanthellae. That doesn't even count other chlorophylls, accessory pigments or even cyanobacterial symbiosis, which can take advantage of other wavelengths outside of the accepted range. In any case, the point being that PAR is still considered the photosynthetic gold standard, both in the field and hobby level. We do know that at least some corals will have a slightly higher efficiency in gathering bluer light, but that is beside the point and probably varies a good deal, especially based on species and maybe even habitat. Foremost is intensity, without which, efficiency doesn't do much good. This is where bluer light is more impractical, because on the theoretical scale, it takes more energy to create blue light than it does to make warmer light. However, when light hits the photosystems, a photon is a photon. Yes, again, the various pigments are slightly more efficient at using blue light in at least some corals. But if the concentration of photons is not there, it is meaningless. That is where PAR comes into play. Intensity is what primarily drives photosynthesis and, subsequently, growth in the wild. In a nutshell, colors warmer than blue accomplish things all day long on the reef--it has higher PAR. That's largely why you don't see the same kind of thick, massive assemblages in deeper water. That doesn't mean that there aren't ones at greater depths, since that is based on a number of variables like clarity, but in general that is the case.

 

From an aquarist's point of view, that means that when we can make more efficient warmer colored lamps (etc.) like we have focused so hard on bluer ones, they will be brighter and more efficient than comparable bluer ones by simple physics. More light and less energy = better in my book. Then again, I also want naturally colored light. The reefs I've visited didn't have the kind of light I see emitted from a Radium or some of these bluer lamps/LED setups. I might see that kind of light on a reef face, but not usually the reef proper. So for me, at least, I see less need for bluer lamps and light than I do for overall intensity within usable wavelengths. Just about anything from 6500K to 12000K provides more than enough of a spike in blue spectra to satisfy practically all corals, minus ones that prefer less intense light in appropriately-based habitats. IMHO, anything more than that is becoming pure aesthetic sense (but not my cup of tea). All that being said, I think I will still stick with my XM 10K lamp .

 

/semi rant

[evilc66]

As Blasterman mentioned (here and previously), the PAR meters we rely on aren't telling the true story. It's all we really have though at this point to rough measurements of our lighting performance.

 

The problem comes from the response curve of the sensor used in the Apogee units (as well as the Licor, but to a lesser extent). In all reality, the Apogee units are really intended to measure terrestrial PAR for plant photosynthesis. As a result, the sensor is weighted more towards red than blue. Great for plants, not for corals. But PAR itself is still a measurement that takes both chlorophylls into account, so we can't ust ignore it. One option is to use PUR as a unit of measurement, but there aren't any off the shelf meters that can measure that, and PUR itself is subjective to the application at hand.

 

The only way to truely measure PAR or PUR is to use a spectrometer, which is out of the realm of 99.9% of hobbyists.

 

neuwave, 6500K cool white LEDs are actually a very good lighting source from the perspective of appropriate spectral output. The balance between red and blue spectral output in a typical cool white LED is proportioned in the same way that the photosynthetic response for corals is. Cool whites have a large blue spike around 450nm, and a smaller red spike around 620nm. If it wasn't for the actual visible color, that's all we would need to grow coral, and grow it well. PAR numbers aren't really inflated as a result.

 

As you correctly noted, PAR does not tell you what the spectral quality of the light is. It's safe to say though, based on current technology, and what we already know, or can assume about the white LEDs used in a particular fixture, that most high power fixtures are more than capable of growing corals without much issue, regardless of what the purported PAR numbers are. The current discussion about LED spectral issues is more to do with color rendition.

[fewskillz]

I thought the par numbers between a royal blue LED and a white LED were the same anyways? Which is why Evil only posts different PAR plots for the different optics, not the different color combos.

[h3llphyre]

The sad thing is most people don't even know what their PAR meter is measuring given most (not all) aren't calibrated for the spectral requirements between tomato plants and acropora.

 

I know *you* know this, but I'd like to expand on this statement. PAR doesn't even account for different terestrial plants, let alone those photosynthetic organisms under the sea. It's a "rough estimate".

 

I've been bouncing the idea around with a friend lately, on how to best describe lighting configs and how to best quantify light sources. I almost wonder if a spectrograph (cheaper to buy/make) combined with a luminosity meter (also cheaper to buy/make), would give us a better idea. Spectrograph gives relative intensity at different spectra, luminosity meter gives overall "brightness", knowing the characteristics of how each meters light, you can infer actual brightness at each spectra. yes, I know i used incorrect terminology for some of this stuff

 

Basic idea... Holographic Diffraction Grating + linear photodiode array +back of the envelope calibration = spectrograph. Commercial lumens meter with a decent data sheet (spectral response) + DIY spectrograph + simple software for math = DIY Spectrometer.

 

This would be great for trying different LEDs and being able to actually tell their spectral bandwidth (for single color) or where the peaks exist and the subsequent bandwidth at each (for whites). This would also be useful for optics and LED placement in arrays, to determine any "gaps" in coverage, both in terms of spectrum and in terms of sheer illumination.

[evilc66]

Right. That's where PUR plays a more important role, but one that's also harder to quantify.

 

You know, I find this almost funny that in the years that reefing has been a hobby, and we have had reef specific lighting, it hasn't been until very recently that we have really started to annalyze the spectral qualities of our light sources. It hasn't been until LEDs came about that it's even been questioned. We just accepted that the bulbs that are available are what we need.

[blasterman]

I use an even simplier trick. The blue channel in my dSLR is uses a 455nm cutoff, and most digital sensors are similiar. I just take manual exposures of different tanks and look at the blue channel. Sounds crude, but it's proven pretty good at relative comparisons of different tanks. Beats a PAR meter showing a number on an LCD display without understanding how that number is derived. I've used this technique to show a local reef shop that one of their tanks that was burning their Acropora was throwing 3x as much blue energy as their show tank even though both were visually similiar, so the technique works.

 

Also, I've tested various color LEDs with narrow optics on Acropora frags, and the only color that caused issues was blue. I could bleach an acropora with a 3watt Cree in less than two days with a narrow optic. A cool-white R2 at the same wattage and angle did nothing. So, it's possible that the other colors in white LEDs act on the protective pigments in hard corals allowing them to tolerate and perhaps regulate light better. This might explain why Acropora farms have better growth results with lower kelvin halides than higher kelvin halides. Perhaps blue best fuels photosyhthesis, but other colors (likely green) allow the coral to regulate it better.

 

I agree with the color thing. I can't stand these deep blue reef tanks with monochromatic color, and some halides aren't much better. Some of the reef lights are going into super high kelvin territory which means they're nothing but blue plus green and a few photons of amber/red. I've found spreading the spectrum with warmer LEDs leads to a wider palette of colors, but it's an aethestic thing.

 

Adding to what Evil just said, it used to be that changing your halides was akin to the local nuclear plant changing fuel rods; lots helicopters hovering around and guys with suits sweating profously. At least with LEDs with have exact control of the spectra we're using.

[neuwave]

Wow I never thought I would get this great of technical feedback. thanks guys!

 

Evil I found it just as funny that not untill now that leds have hit the market for aquariums that we are looking harder at the spectrum, par, etc. We just took it for granted for the most part. In aquarium usa I read an article that spoke of blue being an important part of the spectrum for coral growth compared to some growth ideas of less blue. "But maybe a balance of both blue and 6500k is best? Which not only gives the coral the correct pigment but growth at the same time. Like in humans, we need sunlight to help process vit D. Sure we can go without it for long periods of time but it has negative effects on our body chemistry. Hence why people in some of the colder regions where day light is sparce, expose themselves to uv light.

Also as light travles through water, as we all know blue goes down the deepest. So alot of corals are exposed to the light spectrum a bit more than red, etc. So are we underestimating blue? Confuses me.

I'm sure you forgot by now, evil but I posted a link in one fo your threads before about use of leds back in the 1999 Anyway I just found such a link. Take a look guys:

 

Spectrum effect from led

 

Gives you food for thought about the light spectrum that can either harm or help survival and growth.

 

Now I'm getting my digital camera back this week. To show you guys some odd things happening to my one of my aquarium inhabitants. One in particular, my RBTA.

 

tI was with my past roommate, anther reefer. I had just installed my diy cree royal blue and cool-white leds. Playing around with the dimmers we decided to turn off all the white and just use blue at about 40%. We just wanted to see the colors. lol

A little background- I've had this nem for years, about 4 or 5, I've lost track. It was about the size of golfball when I got it with plump bubbles. Then as most noticed they loose their bubbles as they get older in the aquarium. Just as mine has done considering its current massive size, about dinner plate size when fully expanded. I have yet to observe a full bubble in about 3 years.

 

Now back to the present, watching the tank under only royal blue. About 20-30 minutes of coral watchin (yes I know we are addicted to reefing) my roommate says, is it me or is your rbta changing? I thought, no more beer for you. Once my attention was taken away from my bumble bee shrimp I looked up and saw bubbles! What the heck? The tentacles started to inflate and bubbles started to form at the base of the tentacles and after 45 mins the newly forming bubbles starting making their way up to the tips. Not all the way to the top but almost 3/4 of the way up the tentacle. I will get pics hopefully this weekend. But what the heck is happening? Could this suggest that the blue spectrum is important for the formation of the bubbles but the red is for the growth? I don't know. Have you guys noticed anything different with yours?

[redfishsc]

You bring up some good points but I'd like to comment on this one:

 

When I went to macna alot of the led vendors were so hyped up on the amount of par they could put out. But they mostly used white to up their par. .......It seems like the new fixtures are using alot of white for the par crazy people

 

 

The vendors may think they are getting better PAR numbers by using more white, but they're probably mistaken. White LEDs don't necessarily produce more PAR than their blue equivalents.

 

 

I know that my royal blue XRE's actually put out a bit more PAR than my cool white XPG (which is supposed to be higher in output at the same current). At least, according to the PAR meter I've borrowed. Both are driven at about 1000mA and use 60 degree optics, yet the blues consistently give higher numbers.

 

 

Given that this meter likely under-reads the blue spectrum, these numbers are even more telling.

[blasterman]

The vendors may think they are getting better PAR numbers by using more white, but they're probably mistaken

 

Ah, but maybe it's intentional. Light builders are quick to show how their newest fixture compares to another, but as we've discussed, PAR meters don't all see things the same way.

 

For instance, the Chinese make *terrible* white LEDs. Unless they're turning the factory over on the night shift and making name brand knock-offs they have no clue how to make efficient whites. 100 lumens per watt of white from a Chinese emitter? ROFL. But......the Chinese can make pretty competitive blue LEDs because it's much simplier technology. So......when you advertise your light you'll use a PAR meter that's blue weighted. On the flip side I've caught some Cree based makers show astronomical PAR numbers when it's obvious they're measuring more than blue.

 

The good news is that most of the LED lights were seeing and building are over-kill for even Acropora anyhow.

[kthehun89]

http://reefbuilders.com/2010/09/29/true-violet-led-420/

 

relevant

[evilc66]

 

Also, I love these discussions. Part of what makes NR so great.

[h3llphyre]

I use an even simplier trick. The blue channel in my dSLR is uses a 455nm cutoff, and most digital sensors are similiar. I just take manual exposures of different tanks and look at the blue channel. Sounds crude, but it's proven pretty good at relative comparisons of different tanks. Beats a PAR meter showing a number on an LCD display without understanding how that number is derived. I've used this technique to show a local reef shop that one of their tanks that was burning their Acropora was throwing 3x as much blue energy as their show tank even though both were visually similiar, so the technique works.

 

Yeah, for very rough estimates, I can see this being useful.

 

Also, I've tested various color LEDs with narrow optics on Acropora frags, and the only color that caused issues was blue. I could bleach an acropora with a 3watt Cree in less than two days with a narrow optic. A cool-white R2 at the same wattage and angle did nothing. So, it's possible that the other colors in white LEDs act on the protective pigments in hard corals allowing them to tolerate and perhaps regulate light better. This might explain why Acropora farms have better growth results with lower kelvin halides than higher kelvin halides. Perhaps blue best fuels photosyhthesis, but other colors (likely green) allow the coral to regulate it better.

 

It could just be again, the absolute level of blue. Cool white LEDs have a lot of blue, but not the absolute amount that a straight blue would have. Although, you could certainly be right, as I think there is probably a lot of truth to the regulation of photosynthesis by other colors.

 

I agree with the color thing. I can't stand these deep blue reef tanks with monochromatic color, and some halides aren't much better. Some of the reef lights are going into super high kelvin territory which means they're nothing but blue plus green and a few photons of amber/red. I've found spreading the spectrum with warmer LEDs leads to a wider palette of colors, but it's an aethestic thing.

 

I reef because I like looking at my setup. If I were just growing frags, it would be a different story, so I whole heartily agree with you.

 

 

 

 

Right. That's where PUR plays a more important role, but one that's also harder to quantify.

 

You know, I find this almost funny that in the years that reefing has been a hobby, and we have had reef specific lighting, it hasn't been until very recently that we have really started to annalyze the spectral qualities of our light sources. It hasn't been until LEDs came about that it's even been questioned. We just accepted that the bulbs that are available are what we need.

 

Well, when you can more accurately control the spectrum emitted, it becomes more important to study. Before LEDs became powerful enough (and cheap enough), you took what you could get.

[h3llphyre]

The good news is that most of the LED lights were seeing and building are over-kill for even Acropora anyhow.

 

I don't know if I'd call this "good" necessarily. haha

 

I often wonder if we're just flushing money down the toilet, utilizing the "best" LEDs we can get. Is it really that important to use the most efficient Cree LEDs? Cost/performance ratio on the lower binned (and subsequently lower cost) parts may actually be higher. We already know we don't need to run the LEDs at their full potential (1000mA). That leads into the cheaper chinese knockoffs. Reliability aside, for 1/3 the cost, taking a 20% efficiency hit doesn't seem like a bad deal.

 

To add to this, I think I may do a lil study on the different LED drivers to see where their efficiencies are at. Aka, maybe it's better to spend the money on a high efficiency driver, rather than high efficiency diodes. Just a thought.

 

Also, I wonder how much spectral drift there is over current and temp on LEDs

[neuwave]

I'm so glad this thread has great feedback and thoughts. After all this I wish I could see an actual spectro analysis of my LEDs.

[evilc66]

I don't know if I'd call this "good" necessarily. haha

 

I often wonder if we're just flushing money down the toilet, utilizing the "best" LEDs we can get. Is it really that important to use the most efficient Cree LEDs? Cost/performance ratio on the lower binned (and subsequently lower cost) parts may actually be higher. We already know we don't need to run the LEDs at their full potential (1000mA). That leads into the cheaper chinese knockoffs. Reliability aside, for 1/3 the cost, taking a 20% efficiency hit doesn't seem like a bad deal.

 

To add to this, I think I may do a lil study on the different LED drivers to see where their efficiencies are at. Aka, maybe it's better to spend the money on a high efficiency driver, rather than high efficiency diodes. Just a thought.

 

Also, I wonder how much spectral drift there is over current and temp on LEDs

Typically, yes. The LED setups are overkill for most applications. In some respects though, it can be a good thing, especially if you can adjust the output via dimming, or just height control. At that point, you can add more light as the tank requires. Sure, it costs a little more up front, but saves you having to add/change things once you need more light. Also, as you are running at lower currents, it's running more efficiently anyway.

 

Most Chinese LEDs don't give me a warm and fuzzy feeling, mainly from a reliability standpoint, but there are some companies that are improving that. The G1 Maxspects were a prime example, showing pretty severe output loss and some spectral shift after a very short period of time. While it may seem nice to get the same relative performance and pay less, do you want to do that at the cost of reliability and consistancy? Also, as Blasterman has pointed out, most Chinese LEDs have horrible white characteristics, making the color rendition issue that we have been talking about even worse.

 

I'm so glad this thread has great feedback and thoughts. After all this I wish I could see an actual spectro analysis of my LEDs.

I'm hoping to start an LED library soon with spectal plots, and as much information as I can pull from them.

[blasterman]

Is it really that important to use the most efficient Cree LEDs?

 

I have a different take on this, and to prove your point though I've teased more than a few reefers here for building 'over-kill' lights, bragged about their PAR readings, and then had to turn them down 50%.

 

At least in my 'design' opinion; I'd rather see higher powered LEDs and hence use fewer of them. Or, lights powered by stronger clusters. Less LEDs = lower cost and easier design, and this is one advantage of the XP-G and bigger arrays. IMHO, we should be dimming to tweak our color preference. Not dimming because we're using 2x as many LEDs as we really need.

[franklypre]

I agree on some of the LED setups being overkill, it does seem like a waste. However I personnally have a 58g with a 400w halide, so I don't have much room to talk. I'm curious as to why LEDs are not combined with other types of lighting more often. I see the moon lights and I see a few LED/T5 combos, but why is that not a bigger part of the market? Seems to me we've been using MH/PC/T5 combos for years, why not LED/MH/T5s. I really like the 2 PAR38s I have on my 36corner but seems to me like adding a 20k halide or t5s would add some color that LEDs just don't have available. Not to mention cut back on the shimmer a little.

[h3llphyre]

I have a different take on this, and to prove your point though I've teased more than a few reefers here for building 'over-kill' lights, bragged about their PAR readings, and then had to turn them down 50%.

 

At least in my 'design' opinion; I'd rather see higher powered LEDs and hence use fewer of them. Or, lights powered by stronger clusters. Less LEDs = lower cost and easier design, and this is one advantage of the XP-G and bigger arrays. IMHO, we should be dimming to tweak our color preference. Not dimming because we're using 2x as many LEDs as we really need.

 

And that's one of the things I want to play around with, is how to get decent coverage from less LEDs.

 

Maybe someone needs to just make a multi-die package with both cool white and royal blue emitters. Two birds, one stone.

 

 

Not to mention cut back on the shimmer a little.

 

I dunno, I get a LOT of shimmer from my 150W MH over my 10g.

[Mike Maddox]

Don't forget PUR...a very useful measurement when comparing LED lighting.

[blasterman]

And that's one of the things I want to play around with, is how to get decent coverage from less LEDs.

 

Maybe someone needs to just make a multi-die package with both cool white and royal blue emitters. Two birds, one stone.

 

You betcha...either would reduce the cost and complexity of LED lights, and the bigger the light the bigger the advantage.

 

I work with Bridgelux quite a bit, and originally started with these over reef tanks. Right now I have a spare C1202 (1,300 lumens conservative at an amp), but nothing to do with it. Nobody makes a decent blue that can keep up with the beast, and it would take about eight 3watt RBs to catch up. If I had an equivelant blue I could cut the cost of builds over a big tank as much as in half, and the bigger the tank the bigger the savings. I begged Bridgelux to make just a plain blue because it would actually be cheaper, but they weren't interested.

 

Which brings me to my point that the LEDs we're using on reef tanks were not intended for reefing. Cree makes hyper efficient cool-whites simply because they can sell a lot of them to make street lights. It's industrial coincidence that they just happen to provide really good PAR. Metal halides on the other hand and T5s *do* have versions built specifically for reefing.

 

We've been talking about this in the aethestics thread, and if you were to design an LED specifically for reefing the first big change would be to drastically reduce the green component.

[evilc66]

Don't forget PUR...a very useful measurement when comparing LED lighting.

 

...That I mentioned a few times before? Problem is though, there is no simple way to quantify it, and it takes expensive equipment to do even that. While it's an accurate measurement, it's not a very useful one right now.