Lighting Website Updates

[Gobie74]

The AI unit is modular ( comes in 1 foot sections ) and the leds themselves are easy to take out and replace ( i had to open mine up to remount something that moved in shipping ). Overall, I'm really happy with it so far, but it's only been a few days so I can't say too much just yet. But like I said, very happy so far. Watching the sunrise and sunset is just too cool!

 

[Sparkss]

<a href=showthread.php?s=&postid=11068373#post11068373 target=_blank>Originally posted</a> by k9cop1512
Oh, By the way...Easiest way to figure out your KW rate per hr, because of all the other supplier charges, etc.....Take your electric bill and divide by your KWhrs. In Western MA, I'm paying 15.8 cents per KW/hr. Tim

Not all locations have a flat rate utility rate. Most of California, for example, is on a tiered rate structure. For the fist 100% of baseline each month the rate is .12, for the 101% - 300% the rate is .25 for everything above 301% the rate is .37. The baseline is just a few hundred KWH. In the 5 years we have lived in our current house (even before installing our tank) we always hit the 3rd tier each month. The utility rates should be listed on your electrical bill (I thought that was a Federal regulatory law these days, but I could be mistaken ?)

 

[jcltok]

Whats with the watts?

Whats with the watts?

I have always wondered why hobbyists focus on watts. The real question is whether the coral is getting enough light - lumen. At sea level, the sun provides about 2650 lumen per square foot.

The other is PAR - you need 1800 microMol/m2/sec. Any quantum meter will show you. You have to be careful about lights that achieve high PAR by boosting the violet/blue spectrum at the expense of the rest. A balanced spectrum is needed.

You can define better or worse balanced spectrum by looking at the CCT. The CCT of many high Kelvin MH are around .26 X .26 which is too far away from a balanced spectrum. Certain deeply growing corals will do fine, but it makes it tougher to raise a larger range of coral.

A CCT of about .31 X.31 is more appropriate when you have corals that normally grow in a wider range of depths.

 

[hahnmeister]

<a href=showthread.php?s=&postid=11170657#post11170657 target=_blank>Originally posted</a> by jcltok
I have always wondered why hobbyists focus on watts. The real question is whether the coral is getting enough light - lumen. At sea level, the sun provides about 2650 lumen per square foot.

The other is PAR - you need 1800 microMol/m2/sec. Any quantum meter will show you. You have to be careful about lights that achieve high PAR by boosting the violet/blue spectrum at the expense of the rest. A balanced spectrum is needed.

You can define better or worse balanced spectrum by looking at the CCT. The CCT of many high Kelvin MH are around .26 X .26 which is too far away from a balanced spectrum. Certain deeply growing corals will do fine, but it makes it tougher to raise a larger range of coral.

A CCT of about .31 X.31 is more appropriate when you have corals that normally grow in a wider range of depths.

Translated: "I just found reef central"

I think you can rest assured that everyone in this thread knows what you have posted already... you pretty much just walked into the car dealership and told the salesmen what kinds of cars they sell with that last post. Wattage does concern us though as far as what we spend on our utility bills. Being that large reef tanks are using more and more wattage, keeping track of how much we are spending on our reefs as far as upkeep is important.

Here are some websites that may bring you up to speed on where we are at...
http://www.reeflightinginfo.arvixe.com/

...Sanjay has also written a series recently, to fill in the blanks for anyone who didnt already know...
http://reefkeeping.com/issues/2006-02/sj/index.php

http://reefkeeping.com/issues/2006-03/sj/index.php

http://reefkeeping.com/issues/2006-04/sj/index.php

http://reefkeeping.com/issues/2006-05/sj/index.php

As you will see from that last article, your suggestion of a CIE chromaticity (not CCT) of .31x.31 isnt on the market. And CCT is something different, not given by coordinates like you gave.

You will also find that you suggestion of "2650 lumen per square foot" isnt a measure you can use. Lumens are used to give the total output of a bulb, its not used to describe light across a surface... that would be Lux or Footcandles. In reefing, we tend not to use the photometric scale though since its not an accurate measure of radiant energy. So we stick with PAR, or PPFD. 2650 lumen per square foot isnt really a guideline we can use, neither is 1800MicroMol/m2/s. At what point should we have 1800? At the bulb? At the water surface? At the coral? In nature, you get over 2000 at the surface in Hawaii in the middle of winter. The amount we put in our tanks should be much less than this though, at the surface, since our tanks are not 30' tall like in the ocean. If our tanks were getting 1800 at the surface, our corals would be killed, since our corals are from waters that are 5-25m of depth usually in the wild, and are used to intensities often no more than 300-400 (max of 700 for some yellow porites). So its not like anyone needs '1800'... Many tanks have PAR levels of over 2000 near the bulbs if halide (very concentrated light output), or 900 if a tube (T5s). These levels drop off to less than 1000 at the water surface usually, unless you have a very tall tank and need very intense halides (400s) to penetrate to the bottom. Under the surface, light levels usually are 500-600 at most in the first few inches under the water, and often 200 or less at the sand. So where are you getting this '1800' from?

 

[ludiNano]

hey sanjay, love ur site

have u ever tested the ratings on powerpaq 14k
they come w/ the current USA SunPod 1x150W HQI
Fixture

 

[jcltok]

Hahnmeister

Hahnmeister

You state “I think you can rest assured that everyone in this thread knows what you have posted already... you pretty much just walked into the car dealership and told the salesmen what kinds of cars they sell with that last post.” With no malice intended, I guess it would be useful to provide some information for the car salesman. Sorry, JUST couldn’t avoid saying that. It is truly with positive intent that I suggest the following.

You state “As you will see from that last article, your suggestion of a CIE chromaticity (not CCT) of .31x.31 isn’t on the market. And CCT is something different, not given by coordinates like you gave.” Dominant wavelength is derived from the CIE 1931 Chromaticity diagram and represents the perceived color. CIE1931 was the panel that established standards in the year 1931, and CIE ratings are based on CCT coordinates. Attached is a manufacturer’s chart for CCT for LEDs. The bin number is to be able to order the product item you want. Note that particular CCT coordinates indicate different Kelvin. Consider what the coordinates are for a 20,000 Kelvin light source.

I have to attach the file to a separate post since the size of the file is to big!

You state “Lumens are used to give the total output of a bulb, its not used to describe light across a surface... that would be Lux or Foot candles.” Well… a foot candle is the same as a lumen â€"œ 3 foot candles is equal to 3 lumen. I stated “The real question is whether the coral is getting enough light - lumen. At sea level, the sun provides about 2650 lumen per square foot.” I am not suggesting anywhere that 2650 lumen be used at water level in a tank. If you search my other posts, you will find I suggest lower lumen levels for a tank. I simply provided 2650 lumen as a reference point of what the sun does.

You state “So we stick with PAR, or PPFD. 2650 lumen per square foot isn’t really a guideline we can use, neither is 1800 MicroMol/m2/s.” My point was “You have to be careful about lights that achieve high PAR by boosting the violet/blue spectrum at the expense of the rest. A balanced spectrum is needed.” For clarification I mean that high PAR can be achieved but by loading on violet/blue light and not paying sufficient attention to the rest of the spectrum. You have to look at PAR combined with light brightness (Lumen) to create a better aquatic environment. I am sure you have seen high PAR ratings which produce very dim lights. The light output does not provide enough spectrum or lumen to other corals that live higher in the water column.


Your statement of PAR drop-off is correct since there is an inversely proportional relationship between light and distance. You raised this question and I do not know what or how I should respond, but I will it a try based on what I believe you are trying to point out. I repeat â€"œ I do not suggest 1800 MicroMol/m2/s at water level unless you have Elkhorn coral or similar ones that live right at the surface. The amount of PAR you get at different levels within your tank is dependent on the output and distance of the specific bulb from the water. Please direct me to the peer reviewed research that specifies “max of 700 for some yellow porites”. The amount of PAR needed at any depth of a tank is dependent on the needs of the coral in that particular tank. John H. Ryther from the Woods Hole Oceanographic Institute did academic research on plankton. Given that plankton have the same kinds of algae (Cholorphyta and zooxanthelle) as corals, he found that "Saturation intensity of Cholorphyta and diatoms for photosynthetic purposes was reached at 500 to 700 foot candles (foot-candle = lumen/square foot) and for dinoflagellates at 2500 to 3000 foot candles. Photosynthetic activity for dinoflagellates (zooxanthelle - algae also) was reduced by 20 to 30% at intensities 1000 foot candle higher". Ryther however, did not specify depths at which photosynthetic inhibition occurred. I believe this data came from laboratory research.

You state “Many tanks have PAR levels of over 2000 near the bulbs if halide (very concentrated light output), or 900 if a tube (T5s). These levels drop off to less than 1000 at the water surface usually, unless you have a very tall tank and need very intense halides (400s) to penetrate to the bottom. Under the surface, light levels usually are 500-600 at most in the first few inches under the water, and often 200 or less at the sand. So where are you getting this '1800' from?” The PAR level of 1000 at water level is accurate in my survey of light output. MHs are raised to avoid heat transfer and so the PAR and lumen output drop significantly. As an aquarist, that should really matter because the advertised PAR or lumen is not what you are getting at the water level. A quantum meter costing $US200 to measure PAR costs would help identify exactly what PAR you are getting and I strongly endorse it as a useful instrument. As to where I am getting the 1800 MicroMol/m2/s, it comes from taking the “perfect” conditions (2000 MicroMol/m2/s) that you refer to at sea level and account for haze and cloud cover: http://www.wsws.org/articles/1999/jun1999/pollj30.shtml) and (http://earthobservatory.nasa.gov/Study/ArabianSea) to arrive at 1800 MicroMol/m2/s. It really is more like 1700 MicroMol/m2/s, but I found many lens use to protect the bulb reduce output, so I propose 1800 MicroMol/m2/s to be safe.

Please feel free to raise any other questions regarding my posts as I do enjoy talking about lighting.

Regards,

 

[jcltok]

CCT File

CCT File

I could not upload the file, so here is a link: http://www.lumileds.com/pdfs/DS56.pdf

Regards,

 

[hahnmeister]

Please direct me to the peer reviewed research that specifies “max of 700 for some yellow porites”.

Dana Riddle 2007. It took the most light of any of the corals he tested. Many others only took a fraction of that. The only organism that was higher (not saying higher light corals dont exist, only that they arent imported) was the crocea clam... it could take whatever you gave it.

As for the exact light output your home reef gets... it all depends on what you want to keep and how tall your tank is. The light levels at the bottom of a tall tank with 400 watt halides could be replicated by a 108 watts of T5s over a 10" tall frag tank. The light at the surface of the tall tank might be 700-900, and at the top of the frag tank, only 300... but in both cases, where the coral is at can still be 200. Thats why I found your suggestions ill-advised.

The other thing to keep in mind (not aiming this at you) is that our home aquaria are usually constant intensity over the course of the day. So calculating MegaMol/m2/day is what you have to do when comparing to nature. A constant intensity of 700 over 8 hours might equal the varying intensity that peaks at 2000 over the course of 11 hours. Comparing corals to what they get in nature seems to be a futile thing though... photosynthesis is all about a balanced chemical equasion. Due to lack of phytoplankton, flow, and other things... this rate will not be similar to what is in nature, so trying to match the light output isnt always the best thing either.

Most of the corals we keep are from 5-20m of depth where the PAR levels drop off very fast. Dana was nice enough to send me a full rundown of daily exposures w/ regards to depth of Corals, microMols/m2/s as well as MegaMol/m2/day. As it turns out, Im clearly overexposing my corals in captivity, yet my daily exposure is lower than what these corals most likely got in nature.

Lumens per square foot... why not just use the term 'foot candles'? Thats what it is. Its like calling a Newton a Kilogram-meter per second squared. Sure they are both right, but no need to make it more complicated.

I dont agree with this though...
"My point was “You have to be careful about lights that achieve high PAR by boosting the violet/blue spectrum at the expense of the rest. A balanced spectrum is needed.” For clarification I mean that high PAR can be achieved but by loading on violet/blue light and not paying sufficient attention to the rest of the spectrum. You have to look at PAR combined with light brightness (Lumen) to create a better aquatic environment. I am sure you have seen high PAR ratings which produce very dim lights. The light output does not provide enough spectrum or lumen to other corals that live higher in the water column."

PAR is the radiometric scale... what is important for corals and photosynthesis (they dont need to 'see', they just absorb the radiant energy). The photometric scale is not as accurate because it doesnt register blue as well... because the scale is based on what the sun makes as well as what our eyes see. But Radiometric meters dont 'boost PAR' by reading the blue levels unfairly... if anything, they are more fair than the Lux meters, since they are not going by what our eyes see... they are going by what the coral sees. I dont get where this comparison to the photometric scale comes from. PAR is the least 'skewed' measure for light around... it measures actual radiant energy, it doesnt measure it unfairly. Do you think photosynthetic organisms give a hoot about how we see the light? Not one bit. And since blue light contains more energy than red (shorter wavelength), it is important for us in this hobby to keep track of it with a PAR meter more than a Lux meter. Blue light can photoinhibit corals much worse than a warmer wavelegth. PAR, in most cases, is really all that matters.

PAR w/ regards to PUR might be worth comparing though. Dana has mentioned that perhaps his earlier review of the Solaris LED's, and putting a high value on the comparatively higher PURAR ratio of the LED's vs other lights may not be the best thing. Too much PUR and too little PAR means the coral may not pigment in very well.

 

[jcltok]

I think this where the confusion lies:


"Radiance flux (ФЄ) is the energy per unit time (dQ/dt) that is radiated from a source with the range of .01 to 1000 μm4, which includes the visible, infra-red and U.V regions. A radiant flux of 1 watt means that the source produces 1 joule of energy per second."

So radiance flux measure a WIDE range of energy that is not good to or useful to coral photosynthesis. I have no interest in the visual aspects of light when I speak of lumen - I focus on the photosynthetic range which also happens to be 400nm to 700nm.

PAR meters - "Quantum sensors measure light energy at the specific wavelengths plants actually use for photosynthesis. All quantum meters measure Photosynthetic Photon Flux (PPF) as µmol 2m-s for Photosynthetically Active Radiation (PAR) in the range of 400 to 700 nm. The meter approximates radiation between 400 and 700 nanometers(PAR) as umol m2-s."

Mind that you can fool a PAR meter by loading on one wavelength. It is unethical but it is being done.

I hope this helps the discussion and explains why I suggest PAR and good Lumen/Lux meters for measuring what light is getting to the water. To me what is being radiated is not important if by the time it gets to the water, it is minimal amounts of energy - there are so many variables that radiance cannot be applied consistently (2 units produce the same radiance, but one is hung 12 inches above he water and the other is hung 18 inches - same amount of radiance but different impact at the water).

What is important is what is happening at the water. Let me also clarify that I do believe different corals need different PAR and lumen - I just haven't seen academic research showing the PAR requirements for each type coral.

I am sure Dana Riddle lives up to his reputation and would urge him to publish in the academic world so we can all see his methodology and analysis. With his experiments, Marine Biology would gain much.

Regards,

 

[jcltok]

Hahnmeister

Hahnmeister

Can you give me the reference information so I can find Dana Riddles research. Thanks I appreciate it!

You state: "As for the exact light output your home reef gets... it all depends on what you want to keep and how tall your tank is. The light levels at the bottom of a tall tank with 400 watt halides could be replicated by a 108 watts of T5s over a 10" tall frag tank. The light at the surface of the tall tank might be 700-900, and at the top of the frag tank, only 300... but in both cases, where the coral is at can still be 200. Thats why I found your suggestions ill-advised.

Hahnmeister - what suggestion? One suggestion I made to another poster on another thread about how much PAR to aim for was based on the work of John Ryther from the Woods Hole Oceanogrphic Institute. Is that the thread you are referring to?

By the way, what is the PAR of 108 watts of T5s (brand please and model number) at what distance from the water? I am sure everyone will appreciate that information!

You state: "The other thing to keep in mind (not aiming this at you) is that our home aquaria are usually constant intensity over the course of the day. So calculating MegaMol/m2/day is what you have to do when comparing to nature. A constant intensity of 700 over 8 hours might equal the varying intensity that peaks at 2000 over the course of 11 hours. Comparing corals to what they get in nature seems to be a futile thing though... photosynthesis is all about a balanced chemical equasion. Due to lack of phytoplankton, flow, and other things... this rate will not be similar to what is in nature, so trying to match the light output isnt always the best thing either."


PAR is not cumulative. PAR is how much light is reaching the coral at this moment in the span of one second per square meter. The light is there or not there. So, why is measuring MegaMol/m2/day useful - I do not understand?

Regards,

 

[jcltok]

Hahnmeister

Hahnmeister

I have to apologize to you - I reread my posts and I did say "you need 1800 uMol/m2/sec". That is not correct - PAR levels should be set depending on the needs of the coral in the tank! So, I understand why you disagree and I did make a mistake.

Regards,

 

[hahnmeister]

"PAR is not cumulative. PAR is how much light is reaching the coral at this moment in the span of one second per square meter. The light is there or not there. So, why is measuring MegaMol/m2/day useful - I do not understand?"

I never thought it was either at first... but I suppose so! Its mentioned in Sprung/Delbeek's last volume (3) in the lighting chapter as well. The daily photoperiod is what is important to the corals. Most of the info Dana and I have talked about has been MegaMol/m2/day. It took some getting used to for me as well. It makes sense though... photosynthetic cells are alot like solar systems and batteries all in one. They 'charge up' and convert radiant energy to the energy the organism needs, as well as for chemical conversion processes for physical mass buildup. So corals are a bit like batteries (plants are as well), and when you look at it like this, yes, the daily photoperiod is what matters. There are limits... like putting a coral under more light than it can handle will just overload its defenses and it will bleach, and putting it under too long of a photoperiod will disrupt the corals night process... but lets say you have a coral that gets 6 hours of light at a PAR of 300, or 9 hours at 200... its the same thing in the end. The higher intensity might cause for more pigmentation to develop to protect the coral (or sometimes this happens in reverse because the light part of the photosynthesis is more than the other energy sources and an imbalance is produced), but thats about it.

If you like PM me your email and I can send you an interesting file of info I asked him for.

 

[hahnmeister]

Between these posts, and the one on this page...

http://reefcentral.com/forums/showthread.php?s=&postid=11197257#post11197257

You need to quit posting as if you know more than you really do. You need to read Sanjay's articles, and consider this: what you think you know may be wrong... very wrong. Im shocked nobody else has jumped on you about this, but you arent helping anyone, and if anything, are steering them down the wrong path. You obviously are new at this, and trying to process information without understanding it 100%. So passing along information that is incorrect seems to be a problem. A university level course on the EM spectrum and optics would be my suggestion as well because some of the calculations that you are arriving at are impossible to get with your methods.

I am willing to help, but you have to just stop. You are spitting out more incorrect info at a time than I can possibly type a correction to.

 

[jcltok]

hahnmeister

hahnmeister

You asked I stop posting - why don't you go read Dana Riddle to whom you refereed me to. You will find that his and my points though stated differently and coming form different base point to the same out comes. I suggest you listen to yourself before you write. Go reread Riddle and learn some things.

 

[jcltok]

Hahnmeister

Hahnmeister

Just how much data do I have to provide for you to listen. Maybe a Physics Professor from the University of Arkansas can explain to you:

You state: "There is no way you can convert lux to PAR/PPFD... you are talking two different things! You need to stop posting bad info. Also, you can not use a meter like that to get a lumen or PAR per watt figure!! It just doesnt work like that. There are reflectors in involved with what you did, so the intensity will vary with position. Lumens per watt calculations need to be done without a reflector, and are done by calculating the total incidental light from every angle around a light source, not by taking any spot readings. It can be determined by a point reading sometimes, if you know what your total area is and how it varies over that area, but you need integral calc to determine this ratio then.

You need a physics course on optics and the EM spectrum. Seriously... your info is just not right. You arent helping anyone.

Im shocked that Bean hasn't jumped on you already."

Here it is...

Date: Mon Jul 31 16:38:51 2000
Posted By: Jeff Robertson, Faculty, Physical Sciences, Arkansas Tech University
Area of science: Physics
ID: 964457090.Ph
________________________________________
Message:

Light measurements can be complicated but illuminating...

Photometric units, illuminance:
Footcandle = one lumen per square foot. The 16th General
Conference on Weights an Measures (CGPM), Oct. 1979, decided that the candela is the luminous intensity of a source emitting monochromatic radiation of frequency 540 x 1012 Hz and radiant intensity 1/683 watt per steradian. This corresponds to 683 lumens per watt of radiation at approximately 555 nm wavelength, which is near the maximum of the standard photopic spectral luminous efficiency curve.
Lux = one lumen per square meter.

Quantum units, photon flux density:
Microeinstein per second and square meter (µE m-2 s-1). The
einstein has been used to represent the quantity of
radiant energy in Avogadro's number of photons and also
Avogadro's number of photons. The second definition has the
einstein equal a mole of photons, While commonly used as a
unit for photosynthetically active radiation (PAR),
the einstein is not an SI unit.
Therefore: microEinsteins per m2 per second is identical to
micromoles per m2 per second.
(1000 µE m-2 s-1 = 1000 µmol m-2 s-1)
Micromole per second and square meter (µmol m-2 s-1). This term is
based on the number of photons in a certain waveband incident per
unit time (s) on a unit area (m2) divided by the Avogadro
constant (6.022 x 10e23 mol-1). It is used commonly to
describe PAR in the 400-700 nm waveband.

The approximate conversion factors given below will help to
convert absolute energy units or irradiance units (PAR)
as recommended by the plant scientist into illuminance
or photometric values (lux).

Radiometric PAR - Photometric
Source* W m-2 µE m-2 s-1 fc lux

HP Sodium 1 5 33.5 360
(400 w) 1 6.7 72.3
1 10.8

Metal Halide 1 4.6 29.6 319
(400 w) 1 6.5 69.5
1 10.8

Mercury 1 4.7 30.8 332
(400 w) 1 6.5 70.0
1 10.8

CW Fluorescent 1 4.6 34.2 367
(215 W) 1 7.44 80.0
1 10.8

To convert from either W m-2 or µE m-2 s-1 to photometric units, multiply by the appropriate factor." Here is the hyperlink: http://www.madsci.org/posts/archive...36947.Ph.r.html

SO TO REPEAT The approximate conversion factors given below will help to convert absolute energy units or irradiance units (PAR)
as recommended by the plant scientist into illuminance
or photometric values (lux). That is what you specifically said could not be done.

Charmed by your graciousness!

 

[jcltok]

Hahnmeister

By the way here is a hyperlink to show illuminance conversions for the things you say can't be done:

http://www.onlineconversion.com/illuminance.htm

 

[NewSchool04]

Wow, this is a very interesting conversation! I'm learning a lot in a round about way for an old History major!!

I had a ? that I hope either of you could answer. I run 3 400W Reeflux 10K bulbs on Coralvue E Ballasts. I shut each one of the lights off for one hour, 1/2 hour apart mid day in the light cycle. Left off, 1/2 hour later middle off, 1/2 hour later left on, far right off, 1/2 hour later left and middle on, far right off, and then 1/2 far right on.

I've heard that this gives the corals a break and allows them to regenerate. Am I wasting my time with this?

Thanks and I hope you both continue this discussion. It's very interesting!

 

[hahnmeister]

"why don't you go read Dana Riddle to whom you refereed me to"

Because it wont tell me anything needed for this 'argument'. Dont get me wrong, Im not saying I know it all, just that I know what things are wrong with what you posted. You told someone that UV exists at both ends of the visible spectrum... just beyond 700nm/red and right before 400nm/purple. Uh... the 700+ range was Infra Red last I looked. If you cant pass the 9th grade, theres no use talking about the SAT's... know what I mean?

You posted:
"Just how much data do I have to provide for you to listen. Maybe a Physics Professor from the University of Arkansas can explain to you:"

Its not a matter of how much. You can post as much as you want, but if its not correct, it doesnt make a difference.

That professor is not correct, at least not in our context. It seems in that case, he is talking about a fixed spectrum (as in, for land plants), so a relative conversion is possible. This is the only circumstance that you can compare PAR to Lumens, and only in a relative aspect at best. Its like asking how much diesel you can use to replace unleaded gas in an engine and get the same power... it just cant be done. Sure, there are relative comparisons for horsepower and torque based on the engines you use these fuels in, but you cant compare them directly.

PAR takes the raw photon count per an area... raw visible radiant energy (radiometric scale). It wouldnt make a difference which planet you are on, or what species you are (how you percieve the light), the PAR would be constant. The photometric scale is scaled to what our eyes see. Its the total photon count, but the blue is only counted at 10%, the green at 100%, and the red at 85% (I know those numbers are not exact, but off the top of my head, thats pretty much what its like). Its because our eyes dont see blue light (only 10% of our cones are tuned to see blue in daylight conditions), so having a very blue light might make it seem very dull to us (or in the photometric scale), yet to a coral, which is more than likely primarily depending on blue light in the first place... it could be very bright.

It may seem extreme, but to convert PAR to lumens is something like asking this: "how much red light does it take to equal a given amount of blue light?"... as if there was some way to keep adding red light until you get blue or something. It just doesnt work like that.

So a 10,000K bulb that looks very bright to us may have a PAR of 400 w/o a reflector at 12", and the matching lux rating might be 800 (unitless ratio number). But lets say you have a 20,000K bulb with a PAR of 400 at 12" w/o reflector... one with a huge 460nm blue spike. Well, a lux meter isnt going to pick this up so well, so it might register at 400 only, even though the PAR is the same. To the coral, what we cant see as well (blue) means very little. In fact, bluer light (shorter wavelength, higher frequency) contains more energy (and needs more energy to produce) than longer wave light (red uses less than green, green uses less than blue). And UV is even harder to make (contains more energy). If you read Dana's articles, you will see how he talks about UV photoinhibition alot... he covers it pretty well. But in the same respect, you could have a coral under 200 micromol/m2/s of light with a daylight spectrum and it could do just fine, but if you switch to a primarily blue bulb of that same 200 micromol/m2/s you could end up photoinhibiting (burning) the coral. This is also why bluer halide bulbs tend to have lower PAR than daylight bulbs... bluer light takes more energy to produce.

So its not that manufacturers are manipulating PAR readings by boosting the blue spectrum. Most mfg's give lumen ratings anyways for their bulbs, so trying to manipulate these readings by creating artificially high blue spikes wouldnt do them much good, as the photometric scale doesnt pick it up as well.

If you want, I can go around to all your posts, quote every piece of untrue info, and we can deal with it one on one to get you on the right track.

 

[hahnmeister]

<a href=showthread.php?s=&postid=11199279#post11199279 target=_blank>Originally posted</a> by jcltok
Hahnmeister

By the way here is a hyperlink to show illuminance conversions for the things you say can't be done:

http://www.onlineconversion.com/illuminance.htm

Lol.... yeah, you need to check your own info there. Notice that there are no conversions from any photometric units to radiometric units. There is no conversion from PAR to lux, or PPFD to lumens, because it doesnt exist. Its old news on this forum... really, stop embarrassing yourself.

 

[hahnmeister]

Here is a list of the 'bad info' you have posted...

1.

<a href=showthread.php?s=&postid=11170442#post11170442 target=_blank>Originally posted</a> by jcltok
I agree with all of the suggestions - since we do not have first hand information of your corals' needs.

In terms of lighting, consider whether they are getting enough light - enough lumen - you need about 15 per square inch. Next is spectrum - is the light covering the 400nm to 700nm in a balanced way? Finally, is there enough PAR - 1200 micrMols/m2/sec is the right amount.

and the correction you made doesnt help...

<a href=showthread.php?s=&postid=11170452#post11170452 target=_blank>Originally posted</a> by jcltok
oops. I intended to say 1800 microMols/m2/sec of PAR.

2. In this thread:

<a href=showthread.php?s=&postid=11170657#post11170657 target=_blank>Originally posted</a> by jcltok
The other is PAR - you need 1800 microMol/m2/sec. Any quantum meter will show you. You have to be careful about lights that achieve high PAR by boosting the violet/blue spectrum at the expense of the rest. A balanced spectrum is needed.

You can define better or worse balanced spectrum by looking at the CCT. The CCT of many high Kelvin MH are around .26 X .26 which is too far away from a balanced spectrum. Certain deeply growing corals will do fine, but it makes it tougher to raise a larger range of coral.

A CCT of about .31 X.31 is more appropriate when you have corals that normally grow in a wider range of depths.

3.

<a href=showthread.php?s=&postid=11176310#post11176310 target=_blank>Originally posted</a> by jcltok
What is the depth of a 30 gallon tank? Light output is inversely proportional to distance. If your tank is less than 2 feet tall, then I suggest about 1200 lumen per square foot.

Watts are not the important question - the real question is how much light are you getting at water level? A bulb may be more efficient at turning electricity into light, so watts are not a useful guide.

Second question is what is the PAR. Better PAR with a balanced spectrum produces a better aquatic environment.


Heat from the lights is likely to be an issue with 30 gallons - make sure you find a way of getting that heat away from the water.

4.

<a href=showthread.php?s=&postid=11176472#post11176472 target=_blank>Originally posted</a> by jcltok
...1. You replace 175 w MH bulbs every six to eight months due to phosphor degradation. Using $75 for each bulb as an average, and having two bulbs in one hood, means $300 a year more or less. 2 96w Actinics at $30 each every six months adds $120. You are now spending around $420 just for the bulbs annually.

5.

<a href=showthread.php?s=&postid=11176793#post11176793 target=_blank>Originally posted</a> by jcltok
By the way, the sun produces 1800 microMols/2m/sec of PAR. So the fluorescents at 200 to 350 PAR are a little low compared to 1800.

6.

<a href=showthread.php?s=&postid=11188602#post11188602 target=_blank>Originally posted</a> by jcltok
I am not a physicist, but as a manufacturer of LED lighting, I can respond to your statements and questions.

...3. You seem to confuse PAR with light output. They related but not the same. Light output is based on lumen and can be measured by a lux meter and then converted to lumen. You can also use a lumen meter to measure if the instrument has that function.

4. PAR has been used in reef lights because of research by Ryther at Woods Hole Oceanographic on plankton showing the lighting needs of the plankton algae which happen to be the same species of the symbiotic algae found in stony corals. PAR, measured with a quantum meter, should measure the output of evenly distributed 400nm to 700 nm wavelengths. PAR has been manipulated as you state. Many MH manufacturers add exceptional amounts of violet/blue phosphors at the expense (lack) of other wavelengths, to manipulate the quantum/PAR meter into reading higher PAR.

5. PAR manipulation success depends heavily on the ignorance of users and their unwillingness to publish even their manipulated PAR results. Why? Because sea water level PAR should be about 1700 microMols/m2/sec and the manipulators are putting out maybe 300 or 600 PAR. The PAR of LEDs can also be manipulated by adding more blue color LEDs and minimizing the count of white LEDs. The same logic applies to adding phosphors to MH to manipulate PAR. That is why you see deep blue but very low light LED fixtures. The trade off is lower manufacturing costs, higher Kelvin ratings and faint light.

6. Lumen out put at sea level is 2600 lumen per square foot or 18 lumen per square inch. Lumen and PAR should be measured at the water level, and not at the source. The reason is that light output is inversely proportional to the distance it travels - the farther the light is, the dimmer it is. So high lumen - brightness is necessary. MH will reduce their light output and change spectrum very quickly which is why they should be replaced every six/eight months. LEDs if kept at proper operating temperatures, do not change lumen or spectrum until after 30,000 hours - assuming you buy the best product.


7. Kelvin ratings are a measure of COLOR COORDINATE TEMPERATUREs which can be measured by instrumentation. Higher Kelvin does not mean better PAR. Higher KELVIN means bluer light. Why is this relevant? Because corals grow at different depths and some grow in the violet/blue light - hobbyists think that is what they need and it looks cool! Unfortunately many corals live in a higher water level and do not get the spectrum they need. Also actinics make corals fluoresce and therefore leads people to bluer lights.

10. Spectral graphs are provide in "relative output" - in other words the proportion of one wavelength in comparison to others. In high Kelvin MH you see a huge spike in blue and minimal in the rest of the spectrum. In LEDS, you can expect a spike in the blue, a dip in the 475nm range, a rise in the 500nm tapering off to near infrared. (700nm). LEDs are not the perfect solution either - they happen to be better than MH and Fluorescents. Keep in mind that what I have stated above assumes the best LED available and not just any LED. I have not stated which LED is best on the basis of published data because that is not appropriate in this forum! I can be reached at jcltok@cox.net

7.

<a href=showthread.php?s=&postid=11195647#post11195647 target=_blank>Originally posted</a> by jcltok
I think this where the confusion lies:


"Radiance flux (ФЄ) is the energy per unit time (dQ/dt) that is radiated from a source with the range of .01 to 1000 μm4, which includes the visible, infra-red and U.V regions. A radiant flux of 1 watt means that the source produces 1 joule of energy per second."

So radiance flux measure a WIDE range of energy that is not good to or useful to coral photosynthesis. I have no interest in the visual aspects of light when I speak of lumen - I focus on the photosynthetic range which also happens to be 400nm to 700nm.

PAR meters - "Quantum sensors measure light energy at the specific wavelengths plants actually use for photosynthesis. All quantum meters measure Photosynthetic Photon Flux (PPF) as µmol 2m-s for Photosynthetically Active Radiation (PAR) in the range of 400 to 700 nm. The meter approximates radiation between 400 and 700 nanometers(PAR) as umol m2-s."

Mind that you can fool a PAR meter by loading on one wavelength. It is unethical but it is being done.

I hope this helps the discussion and explains why I suggest PAR and good Lumen/Lux meters for measuring what light is getting to the water. To me what is being radiated is not important if by the time it gets to the water, it is minimal amounts of energy - there are so many variables that radiance cannot be applied consistently (2 units produce the same radiance, but one is hung 12 inches above he water and the other is hung 18 inches - same amount of radiance but different impact at the water).

What is important is what is happening at the water. Let me also clarify that I do believe different corals need different PAR and lumen - I just haven't seen academic research showing the PAR requirements for each type coral.

I am sure Dana Riddle lives up to his reputation and would urge him to publish in the academic world so we can all see his methodology and analysis. With his experiments, Marine Biology would gain much.

Regards,

And then everything you have posted here since.