does lux matter at all?

[2smokes]

From the link you posted ,this http://www.advancedaquarist.com/2013/2/equipment You can see a PAR meter is just a light sensor (just like the lux meter have) that has coloured filters to measure only red and blue light.This is a scheme from that article you posted

It doesnt measure whoole spectrum like my diy spectrometer would if i would have build it.More info about the diy spectrometer here http://www.reefcentral.com/forums/showthread.php?t=2606060

 

[jason2459]

From the link you posted ,this http://www.advancedaquarist.com/2013/2/equipment You can see a PAR meter is just a light sensor (just like the lux meter have) that has coloured filters to measure only red and blue light.This is a scheme from that article you posted

It doesnt measure whoole spectrum like my diy spectrometer would if i would have build it.More info about the diy spectrometer here http://www.reefcentral.com/forums/showthread.php?t=2606060

Again, we go in circles. This fully is answered and questioned again already.

There is a difference between filter and sensor. Did you read the full article and the wavelengths measured? I've read many chinese marketing materials translated horribly to english.

Looks like a fairly decent range that we care about in this hobby.

Spectral Range: 389 to 692 nm ± 5 nm (wavelegths where response is greater than 50 % of maximum)
Spectral Selectivity: Less than 10 % from 412 to 682 nm ± 5 nm
Directional (Cosine) Response: ± 5 % at 75° zenith angle
Azimuth Error: Less than 0.5 %
Tilt Error: Less than 0.5 %
Temperature Response: -0.11 ± 0.04 % C-1
Uncertainty in Daily Total: Less than 5 %
Detector: Blue-enhanced silicon photodiode

2smokes, Have you provided a linking saying there are no par meters that can detect anything at all other then blue and red? I might have missed it.

From what I'm seeing and have posted a reference to above is that they can measure a wide range of wavelengths.

This is something that would effect anyone that has used or bought a par meter.

Its been known that apogee par meters have had some issues with reading the proper amount of "blues" when it comes to LEDs. Which flys against what you are proposing as part of one of only two colors they can detect.

The latest apogee meter is supposed to help correct for that.

Actually I posted a link to an article testing individual colors of an LED light system. Including Green and several other colors. Or did you miss that part?

 

[gus6464]

It's pointless arguing with him about this since he has no clue. A truly accurate par sensor's quantum response should be flat between the violet to red spectrum.

He is confusing par with pur which is a totally different thing.

 

[jason2459]

I think I can trust Dana Riddle to not make us believe measurements that were measured couldn't possibly be measured.

Here's another good definition of a par meter in this comparison article.

http://www.advancedaquarist.com/2005/7/review

"PAR meters (also called quantum meters) are the preferred instruments for measuring light intensity when photosynthesis is involved. Ideally, quantum meters measure (and report as equal) the amount of energy in light wavelengths between 400nm and 700 nm, and report it in units of micromol per square meter per second (µmol·m²·sec). Full intensity sunlight is generally ~2,000 µmol·m²·sec. 'Micromol' is the preferred unit for reporting purposes, as opposed to 'microEinstein', a unit that is commonly used in older literature. However, any measure of PAR or PPFD (either µmol·m²·sec or µE·m²·sec) are still somewhat of 'outlaw' units, not recognized as SI units, and something of buzzwords to those obsessed with botany or phycology."


And if a par meter can ONLY detect blue and red why would one have issues with blue (again recently revised)

"Spectral Response
Spectral response has been the loudest argument used in debates of comparing measurements between brands of quantum meters. A quantum meter sensor's ideal spectrum response would report as equal the energy in each wavelength between exactly 400nm and 700nm. However, neither the Li-Cor nor the Apogee response is ideal. The Apogee underreports blue wavelengths more so than the Li-Cor. The cutoff in the red portion of the spectrum is at ~650nm for the Apogee; the Li-Cor sensor extends its range (albeit slightly) into the near-infrared (cutoff at 700nm, but with a slight response to ~720nm). Near-IR radiation can cause substantial errors in certain cases."

 

[jason2459]

It's pointless arguing with him about this since he has no clue. A truly accurate par sensor's quantum response should be flat between the violet to red spectrum.

He is confusing par with pur which is a totally different thing.

Pur is coming up more vs Par. I would be interested in learning more about that.

 

[2smokes]

You are funny and you act like you are PAR meter sellers.Off course it measures the entire spectrum(the source of light) but it only measures the red and blue colors from that entire spectrum .A par meter has its filters to avoid measuring green and yellow and any otther colors except red and blue.The guy thats saying i have no clue about light is the guy that sayd a par meter measures green also...Funny.

 

[jason2459]

You are funny and you act like you are PAR meter sellers.Off course it measures the entire spectrum(the source of light) but it only measures the red and blue colors from that entire spectrum .A par meter has its filters to avoid measuring green and yellow and any otther colors except red and blue.The guy thats saying i have no clue about light is the guy that sayd a par meter measures green also...Funny.

What are you talking about? Technically everything is shifted to the "red"or "blue" (see dopplar shifting) if you really want to try to make everything "black" and "white" or in this case red and blue.

What spectrum are you talking about that red and blue covers its entirety?

The "visible" spectrum is very narrow and blue is only one small part of it. The apogee is rated to cover a good chunk of our visible sliver of a spectrum. Which includes more then just Red and Blue.

http://science-edu.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html

 

[jason2459]

It's pointless arguing with him about this since he has no clue. A truly accurate par sensor's quantum response should be flat between the violet to red spectrum.

He is confusing par with pur which is a totally different thing.

Thanks and I can see the PUR is interested mostly in those two wavelengths.

How accurate the information is on this site I don't know but its an interesting read and breakdown of LUX, Kelvin, PAR, PUR, PAS, etc

http://www.americanaquariumproducts.com/aquarium_lighting.html

 

[gus6464]

Pur is coming up more vs Par. I would be interested in learning more about that.

PUR is basically just the wavelengths that are used in photosynthesis and nothing else. So basically 400-500nm and 600-660nm give or take. Then there is the issue of what is more beneficial? A light that is lower PAR but very high PUR or vice versa.

The violet spectrum falls into this category. A good example are true actinic bulbs. So for example they are 99% PUR whereas a blue+ is more like 80-90% because of it's spike in the green region. So which would actually benefit the plant/coral more. Now of course 420nm is chloro a and 450nm is chloro b but the question it proposes is if let's say you have a spare spot in your light for an extra bulb would you fill it with a bulb where 99% of the spectrum emitted is absorbed for photosynthesis or a bulb where 85% of it is but has more par the other one.

High PUR has become a lot more common in planted tanks in favor of just high PAR. It is entirely possible to light a reef tank with high PUR and low PAR now with the creation of lime/mint leds. I know of someone who has custom LED pucks that are comprised of blue, violet, high cri warm white with a one or two lime leds only. Since the human eye is extremely sensitive to green and yellow all you need is a little lime to not have the tank show all blue. So he cranks everything but the lime which is only used for aesthetics. Has less PAR than most but his SPS don't act like it.

I tried it on my last planted tank as well. My 4 bulb fixture had 2 red bulbs, 1 violet bulb and a single 10k white bulb for aesthetics. My PAR was considered super low for having a 4 bulb T5HO in that tank at 60 but I had to pump just as much CO2 into the tank as when I was running starcoat 6500K bulbs and my PAR was almost triple. That was my most successful planted tank when I ran high PUR and I had never before seen erios flower and split so damn fast.

Ohh and a very high PUR/low PAR lighting system would show almost ZERO lux because of no output in green/yellow which totally contradicts what he is trying to say.

This light review shows why LUX is an extremely **** poor way of measuring light output in our tanks.
http://www.danireef.com/2013/11/28/led-fixture-sicce-gnc-am-466-in-depth-review/

19K LUX and over 500 PAR. If the person was only going by the LUX number they would think ohh my corals are getting no light so I need to crank them more. Hello cooked corals.

 

[alton]

LUX/Foot Candle Meter great for telling us when our lighting drops off, and we need to change lamps or adjust leds. It also can tell us how good our leds are by using it at the same time as our PAR meter. While checking that measurement with my MH's years ago I noticed about a 20% difference. While testing it on a Marineland reef capable there was 2,000% difference. And after a month of testing the led fixture, it burned one of my birdsnest even though the PAR levels sucked.
PAR meter is great when comparing your lighting to the sun, since that is why it was developed. I am learning as I continue to grow my better looking SPS, I don't need 300 to 500 PAR level that I achieved from my MH's, that I can grow it just fine under 100. I believe that is because most of the better looking corals come from deeper in the ocean where all the reds and yellows have been filtered out and only the UV and blue spectrum has survived. And since the newer leds have these covered I am able to make it work. FYI I do have the same corals under 300 to 500 and they do great also, it is just I am amazed they are fine with lower levels.

 

[Ron Reefman]

The problem with PUR is that every coral can have a different PUR depending on what kinds of zooxanthellae it has. There is no one spectrum of light that makes up PUR for all corals. Shallow water corals often use red spectrum some and deep water corals don't use red at all.

And 2smokes, you are just so wrong about PAR meters I wouldn't even entertain getting in the... discussion.