old school buddy.. LUX and Fc are mathmaticly interchangable metric english
Lux Meter, Par Meter, whats the difference??
- Thread starter LostInTheDark
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Vaughn17
Well-Known Member
I have one of those. I'm going to try it...thanks!
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LostInTheDark
Active Member
So for our purposes a Par meter would be the more accurate choice? Would a lux meter suffice as all spectrums should fall off equally?They measure the light differently. LUX measures how the eye sees light, green and yellow are given more weight than red and blue.
PAR measure the light evenly across the visible light spectrum.
The LUX converters work only as well as the light that you are measuring. If the light has a big spike in the blue and nothing in the green, the conversion will be not as accurate if the light being measured was uniform across the whole spectrum.
Yea but thats totally confusing to most.They measure the light differently. LUX measures how the eye sees light, green and yellow are given more weight than red and blue.
PAR measure the light evenly across the visible light spectrum.
The LUX converters work only as well as the light that you are measuring. If the light has a big spike in the blue and nothing in the green, the conversion will be not as accurate if the light being measured was uniform across the whole spectrum.
the converters are there to take that into account with MH and tubes. its only really hard with led as you can have much higher par depending on how you mix it.
It doesnt measure it how the eye sees it. it measures the intensity of the visible light spectrum. the only slight drawback is the photcell isnt as receptive to blue and red.
Also A par meter is more similar to a photographers color meter as the results can be scewed by placing a white black red or blue piece of paper next to it.
Look at pictures of Par maps. corals on the same dist from the lamp have different Par readings.
so for most users its a fine indicator and a gateway drug into understanding par. and knowing when to change the tubes.
And the advice above is really, if you have a lamp with a known good spectrum, by tracking the intensity youll likely not under or over light you corals. And if you test and acclimate you have a quantifiable number to go by. Like Alk or mg or No &po
In a perfect world we would all have a Par meter and Lux. Id bet you use the lux more.
the difficulty with the first chart is theres no number to the left. if you squashed and stretched it the difference or "spike" is less noticable.
Are the 2 charts on the same scale?
see my last. In a perfect world both. Par is very interesting in that you dont need intensity to produce par.
@saltyfilmfolks, we understand that you have some if not a lot of knowledge about all this.
Maybe it helps to point the members in a helpful direction on some websites how al to do this, youtube.
What is the difference in getting a PAR from MH/T5 vs LED?
Does the MH/T5 vs LED's count the same way for LUX?
What's the best APP on a LUX for smartphones?
Maybe it helps to point the members in a helpful direction on some websites how al to do this, youtube.
What is the difference in getting a PAR from MH/T5 vs LED?
Does the MH/T5 vs LED's count the same way for LUX?
What's the best APP on a LUX for smartphones?
When this is brought up a Par meter can be placed into the water at the coral position in the water. Lux meter not to be placed under water at least the cheap ones. The value of light above water is way different that what you get below the water due to the attenuation of the light wave in water. I have measured 400 par above the water and 0 par at the bottom of a tank with a fixture. I do Par measurements for my club on all kinds of lighting depending on the club members tank.
Michaelrunner
Active Member
I'm just curious about the conversion. I have the galatica app for my iPhone but what does it mean? How do I read the data or convert it?
Yes sir. I am working on an article to do just that.
I do like to include the links to the research thanks for reminding me to do it here.
I should add them to my signature but I have a really good quote there right now.
advanced aquarist MH T5 Lux par conversion
http://www.advancedaquarist.com/2008/2/review
from Apogee lux par conversion
https://www.google.com/url?sa=t&rct...7D7Ca0kTnSuqMtysJO5xuA&bvm=bv.115339255,d.eWE
advanced aquarist. VERY advanced. led par and also how a par meter works Plus side by side comparisons of par meters and spectral responses.
http://www.advancedaquarist.com/2013/2/equipment
What's your input on the new 500 par from Apogee, it seems a better meter for LED's but will it have some negative effects on reading PAR from T5 or MH?
And as reefwiser has mentioned Par is not to trifled with. you can have PLENTY of intensity in lux and near ZERO par.
I only advise check the intensity, its easy. If your good there begin to question the par. A Kessel you wont have to question its potential par jus if you have it too dim.
I only advise check the intensity, its easy. If your good there begin to question the par. A Kessel you wont have to question its potential par jus if you have it too dim.
It has to be good. Apogee has seemingly been tested closets to purely scientific instrument results in everything Ive read.
And Its made in Provo.
My fear for most reefers is the application of uv. I dont know the 500 does that and what intensity UV is being delivered by the fixture. dangerious. If you cant test for it, dont put it in your tank.
Additionally, the amount and flexability of the higher end led can be tough to guage even with a par meter. to get better par do you bring up blue or red? Only ressearch and experience tells you that.
One reason I like the SB reef light guys is they are explaining what your doing with each individual spectrum and its affect on your coral. Teaching.
Kessel gave me nothing to work with including par specs. Geez
leds are tricky. but if you kook at the conversion factors of the analoge sources in the AA article, guaging by the color temp(14k 20k) you can run some of those comparisons and have a close approximation of what you have.
but once you run into the 40,000 and 50,000 lux are at the top of thank, BE CAREFUL. A radium 20kelvin MH at 50k lux is about 700par.
Can you explain the 40 to 50k LUX as many members who read this will freak out as they are used to PAR readings from 150 low point to 700 high watersurface points?
For you, anything.
Lux is a measurement of light intensity. from 0(dark) to 100,000(average daylight)
Foot-candles are( if you are a photographer,) another standard of light intensity. Metric/english standard so to speak.
PAR is the amount of usable light for photosynthetic organisms. photosynthetically active radiation.
Intensity and color spectrum both play a part in building PAR
Buy measuring LUX (intensity) and using one of the lighting type specific conversion factors listed. you can closely gauge the amount of PAR in that lamp.
http://www.advancedaquarist.com/2008/2/review
In my 30G cube. At the top of the water. I have an average of 40,000 lux of intensity.
I have a Radium Blue Metal halide over it.
40,000 lux/51=784
Lux ÷ Constant = µmol·m2·sec par
now do the same math at at "Only" 25000 lux
25000 lux / 51 = 490
.
interestingly the coefficient of the sun is 51
That is not the saying the color of the light sources are similar spectrally, just that the amount of PAR is similar.
The coefficient of a cool white tube is 74. so at 40,000 lux is 540par. sounds good Right???
BUT the spectrum of that lamp contains High levels of Red Orange and yellow that will grow green Plants(ugly algae for us) way to much,
For an orchid grower like my wife, that is a good thing, and why PAR meters are used in agriculture too. And why we pay special attention not only the PAR(and its component Intensity) but the spectrum contained in the light source.
FWIW I don't concentrate on the intensity of the source, I focus on the spectrum, but, the reason I write these crazy things, is had there been a more clear explanation of this process and relationship, I would have had much greater success in reefkeeping in the past. BY simply adding one tube of good spectrum to increase its intensity. with dimmers now, that's easy. So dont short your self and also dont burn stuff, and acclimate.
Light is just one parameter to be tested. And if its testing well with your API(lux) test than go Hanna(par)
Dude I like this a lot.
I'm going to name a coral after you, no serious thinking about LUX or PAR stay tuned.
alton
Valuable Member
Foot candles is the US standard, Lux is the Imperial standard. Some "Brits" may take offense to the English aspect? To them we speak American and have messed up the English language. Personally I was told as a child we would drop the US System and adopt the Imperial system in the future (which is much easier to learn and use). But that was 50 years ago and that didn't happen.
I agree that the two are confusing but that is just the way it is. Lux was born out of a finding a way to measure light they way humans see it. PAR is measuring the whole spectrum evenly. You can certainly use lux but it will be inaccurate for what we are trying to do. If all bulbs put out the same spectrum you could use a lux meter and then do a conversion and it would be accurate, but that is just not how thing are.
The new apogee meter is just more accurate on the blue side than it had been. Even how it was, it is not wildly inaccurate, I have licor sensors and have found that the old appogee is normally nor more than 10% off in it measuring of blue LED spectrum.
The new apogee meter is just more accurate on the blue side than it had been. Even how it was, it is not wildly inaccurate, I have licor sensors and have found that the old appogee is normally nor more than 10% off in it measuring of blue LED spectrum.
But all spectrum don't fall off evenly. For example, if you hake a lux reading when the lamp is brand new, then take period reading very few months with the idea that when the lux reading falls by 10% you will change the bulb. Even with a conversion chart, if the green/yellow spectrum changes slightly it will measure much more than if the blue spectrum changes dramatically.
Lux doesn't measure the intensity of the visible light spectrum evenly though. 400nm-800nm is the approximate visible spectrum humans can see, but we are most receptive to green and yellow which is why lux measures the way it does, to give a good idea of how human will perceive the light.
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