PAR Quantum Light Meter - LED vs. HPS - Cold start flux output vs. Running

In the thread Lighthouse Hydro is doing it wrong.
I wrote this:

Rasser said:

I'm also looking forward to getting a PAR light meter, besides the obvious tests,
The Sun vs. HPS vs. LED and so on, it would be interesting to see how big a difference
there is in light output between a cold started unit and one that's been running for 30 minutes.
A standart lux meter may work for that test - anyone got one of those?

Click to expand...

And to my surprise my PAR Meter arrived a week before expected.
So I've done some test and I feel that this deserve it's own thread,
and since the other thread already has plenty of info on cooling, modding, LEDs and heat.

Unboxing at work.



It's has turned very hot today, 3 days ago I was wearing long johns.
Great timing for the TempMod I've done on my unit.

I also measured the Sun PAR light output at lunchtime in clear sky and hot temps(82°F+) to be around 1700-1800 units(umol)
and at home around 16:00 I measured the sun again to be about 1500 and 1300 behind 6mm window glass.
So what will my LED lamp show...


Home - First test setup - Cold start !
Unit = 120W(90Watt actual draw) 112 LED's



Ambient light.




Lights One ! 457 umol and dropping quick.



Temperature +5 sec. 92.3°F


After 10 minutes. Temperature is up and due to the high temperature today
I'm running 100% power on the fans.

109.2°F


Ambient temperature:


Drums !



Output has dropped to 436 umol.
I feared it would be worse,,,
so if I was able to keep the plate at 33°c(91F) I would gain 30 unit, not much
considering how much cooling I would have to do to be running at that low temps,
adding some more light to compensate for output is properly making more sense.
( feel free to convert my numbers to % drop )




And a quick test on a 250W HPS(+30W ballast)


The HPS lamp is a bit higher up than the LED, so a real plant could grow there without getting on fire.

Not far from the LED output, and +200 if I close the door to enable more reflection.

BUT !
Reading the manual it's not that easy to compare the to types of lamps. The meter is calibrated to the sun,
and green light is counting too, and it looks like blue don't count as much as red and green.
And there is a small conversion table:

"Quantum light meters are calibrated for sunlight.
Due to differences in the spectrum generated by
artificial light, the following adjustments must be
made in the value shown on a sunlight-calibrated meter."

HPS 0% error vs. the sun = 1:1
CFL reads 8% to high vs. the sun = CFL*0.92= results to compare with the sun.
Metal Halide reads 8% to high = ----- // -----

NO LED conversion factor ! shit, But how could they make one anyway,
who knows what color LED are used.

So I'm a little bit disappointed with my new instruments sensitivity spectrum,
witch looks like this:

A snap from the manual.

"The Chart below displays the spectral response of the Quantum Light Meters."


But the meter is great to see how much light there is around the grow room, and like the
cold start test if you stay within the spectrum.

But using this meter HPS will properly beat LED every time.
And it's properly also the reason that this LumiLight test is using a very expensive spectrum analyzer
with individual bands displayed and not just a plain PAR meter.

Video of a 330W LumiGrow LED lamp vs. 400WMH and a 600W HPS:
http://www.youtube.com/watch?v=DAw13w9eFxY&feature=related

Some screen shoots I captured and added some blue text to.

I think the big number in the overview section at the top is a total of PAR
and the 600W HPS is doing a double vs. the 330W LED, but if you look at
the individual bands where the plants likes it, the numbers are in the LED's favor.

There lamp don't do much UV so they totally ignore that band, off course.







Well the meter confirms my believes that a 120 Watt(actual) LED grow light can replace a 250W HPS

Great post Rasser............so that meter doesn't register far red either?? well it's a nice toy to have......how much??

Edit: Oh btw those readings behind the window pane/ late day sun are really surprising............./God why can't I grow under the sun legally???sucks

PSUAGRO. said:

Great post Rasser............so that meter doesn't register far red either?? well it's a nice toy to have......how much??

Edit: Oh btw those readings behind the window pane/ late day sun are really surprising............./God why can't I grow under the sun legally???sucks

Click to expand...

Thanks !
No it don't look like it can see that far.
I like toys, especially instruments that can measure something hidden or dangerous )
I think I paid around 310$ for both instruments. Should be cheaper in the US without the import customs and vat.

I don't regret it, I'm more like wtf did i miss? - LED Grow Light sends out PAR light - okay and whats that wikipedia
"It's 'Photosynthetically active radiation' often abbreviated PAR"
And how do you measure that? "PAR is normally quantified as µmol photons/m[SUP]2[/SUP]/second, which is a measure of the photosynthetic photon flux (area) density, or PPFD"
And you look at the image:

caption: "Typical PAR action spectrum, shown beside absorption spectra for chlorophyll-A, chlorophyll-B, and carotenoids"

"This handheld quantum meter measures photosynthetically active radiation (PAR) from 400 - 700 nm,
with a range of 0 - 2000 μmol m-2s-1. PAR is more valuable than Lux or Foot-Candles as it measures
only the light used by plants for photosynthesis."

I guess that's how it is, if you don't spend a week studding PAR meter and there use and limitations.

Hey Rasser aren't those Danish laws pretty lax on growing outdoors, their were some guys on here growing in Copenhagen right outside on their balconies in plain sight....
To hell with hps/led grow under that bright ass star

PSUAGRO. said:

Hey Rasser aren't those Danish laws pretty lax on growing outdoors, their were some guys on here growing in Copenhagen right outside on their balconies in plain sight....
To hell with hps/led grow under that bright ass star

Click to expand...

Not relaxed enough, if someone called the police they would properly act to remove a few balcony plants, a single cop or a patrol car
on the street that sees it will maybe let it go, all depends on the persons.

Yes to the Sun, but here at Lat. 055 it's pretty dark 8 month of the year.

Next thing to measure.

How far from a 120w(90W) grow light do the meter has to be, for the numbers to equal that of the Sun.

If i go higher the meter shots upwards towards 1999 and black screen, end of range.
So thats pretty impressive I think, considering the unit is using 1 watts noname LED running at 0.8W





Using green LEDs instead, the meter would properly also go to 1534, but would the plant
grow as fast not if you look on the charts.

My lamp configuration is 112 x 1 Watt LED, 88 Red, 12 Blue, 12 Orange
Wave Length: Red 630nm, Blue 460nm ,Orange 610nm

Right now I have no clue as to what a possible conversion factor might look like, not even if it
should be adding or subtracting, and that's bad.

Another little experiment I made was to put this purple color gel in front of the meter
to see the difference, now that cyan-green-yellow light is stopped, in this spectrum.


The Sun
1640 uMol - without the gel
474 uMol - with the gel covering the sensor.

LED grow lamp
1640 uMol - without the gel -(adjusting the distance to match)
1020 uMol - with the gel covering the sensor.


So that's the numbers, but I don't know what that can be used for right now,
but I'm gonna squeeze 200$ worth of numbers out of this thing and I'm already halfway.

I search google images for a day long PAR measurement chart, but found this thread
http://www.reefcentral.com/forums/showpost.php?p=19777167&postcount=383

Where it looks like the aquarium people knows the score.


I've seen people on grow-forums using one single one of the H150 magentas to grow weed.
I can't help but think they might possibly be onto something with their
stupidly-named " spectral revolution" (what, they're haunted?).

Re PAR: this is a huge giant topic and I won't even pretend to have the education
in the subject needed to talk about it competently. By this I mean - having an understanding
of all of the terms mentioned in this gigantic flow chart seems like about what you would need
to hold a high level discussion on it, but, from stuff that is written for idiots, my understanding
of it is that several of the measures we use are functionally like "MIPS" for computers - they are
"a" number that is generally but not necessarily completely correlated with actual performance at
a task (eg growing stuff). For one - PAR isn't necessarily the greatest thing to use (as with lumen/watt with that guy before).

These PAR measurement units - even accurate ones - tend to "average out" their sensor inaccuracies.
This is from one of LiCOR's sales brochures (the brand used by Sanjay Joshi[1] in his tests, though a different model):




And this is how it look when want that kind of accuracy.
http://www.licor.com/env/products/light/terrestrial.html

So If I had done more research, the conclusion would have been - take it or leave it.
Since the above instruments is in a hole other league.
And green light is still counting equally it seams.

[1] http://www.advancedaquarist.com/2010/5/aafeature2
LED Lighting Tests: Aquaillumination, Blue Moon, Eco-Lamp KR-91, Ecoxotic Panorama
By Sanjay Joshi, Ph.D.

LED lighting for reef tanks is on its way to becoming a reality. Different LED fixtures
address the lighting problem in several different ways, small number of high power
LEDs with optics or with large numbers of low power LEDs with no optics.


That's some serious charts in that article.

Nice work rasser on the collecting all the info, very good thread and some nice info.

Would like to add my 1years experience growing with LED. I've had plants at 5 inches away from the panels (1x240 1x500 Blackstar), with bleaching of the tops, i've had much better results with the panels atleast 7 - 10 inches away, with less bleaching and the upper fans leaves dont get MG def looking symptoms ( i think its bleaching) when panels are close to the tops, Even if the tent temps are at 74 F.

When the panels are to close, plants growth patterns are completely different eg. say the plant had been grown 10 inches away oposed to 5 inches through its growth cycle.

Its best to avoid bleaching from the tops, one thing i noticed, some strains can handle the higher par out put at say 7 inches away but others will bleach at 7inches.

Just my 2 cents from what i've noticed when growing with LED, I've learnt the hard way, but the learning curve has been fun, I've learnt alot from this forum which has helped me solve some problems I've encountered when growing with LEDS.

Peace to all keep the happiness growing

Yes ^^^^^great info Rasser, wonder whats causing those high umol readings on the led panel with the gel vs sun with the gel........interesting

cannabuilding said:

Nice work rasser on the collecting all the info, very good thread and some nice info.

Would like to add my 1years experience growing with LED. I've had plants at 5 inches away from the panels (1x240 1x500 Blackstar), with bleaching of the tops, i've had much better results with the panels atleast 7 - 10 inches away, with less bleaching and the upper fans leaves dont get MG def looking symptoms ( i think its bleaching) when panels are close to the tops, Even if the tent temps are at 74 F.

When the panels are to close, plants growth patterns are completely different eg. say the plant had been grown 10 inches away oposed to 5 inches through its growth cycle.

Its best to avoid bleaching from the tops, one thing i noticed, some strains can handle the higher par out put at say 7 inches away but others will bleach at 7inches.

Just my 2 cents from what i've noticed when growing with LED, I've learnt the hard way, but the learning curve has been fun, I've learnt alot from this forum which has helped me solve some problems I've encountered when growing with LEDS.

Peace to all keep the happiness growing

Click to expand...

Thanks !

I did also see a small amount of bleaching on very young leafs, and moved the unit higher, but that's was before I got the meter,
so I don't know what amount of PAR light they where receiving at that time.

We know that 1500 uMol of PAR from a LED grow lamp is not the same as 1500 from the sun, since all the cyan-green-yellow is missing.
The remaining red/orange/blue properly has to make up for that in the 'average calculations'

So the amount of red and blue in PAR light of 1500uMol is maybe the double of what it is in sunshine of 1500 uMol
Maybe my experiment with the gel will give a clue, and 500-800uMol PAR from LED is equal to the red/blue contained in 1500uMol from the Sun,

But now I will be able to measure the level of PAR if bleaching occur, and have something to relate it to besides distance, so that's great.

NB ! BS240(180w) is also twice the wattage as my lamp, so no wonder that bleaching occur at 5" the red blue light must have been treble the Sun's

PSUAGRO. said:

Yes ^^^^^great info Rasser, wonder whats causing those high umol readings on the led panel with the gel vs sun with the gel........interesting

Click to expand...

I think for one, the filter lets almost all of the LED light through without huge loss, the difference between the to readings is be course the orange at 610nm is damped 95%
and red at 630nm gets damped at god deal too, besides blue. The Sun with it's huge green-yellow light output gets damped very hard.

Rasser said:

[1] http://www.advancedaquarist.com/2010/5/aafeature2
LED Lighting Tests: Aquaillumination, Blue Moon, Eco-Lamp KR-91, Ecoxotic Panorama
By Sanjay Joshi, Ph.D.

LED lighting for reef tanks is on its way to becoming a reality. Different LED fixtures
address the lighting problem in several different ways, small number of high power
LEDs with optics or with large numbers of low power LEDs with no optics.
That's some serious charts in that article.

Click to expand...

I've just read some of the comments on that page and I think this one make sense to post here.

"What is the spectral weight of the PAR meter you used, and is it explicitly calibrated for coral and not tomatoes?
The reason I ask is most PAR meters are weighted towards terrestrial use, and include the function of long wavelength
red which has little benefit to acropora. Because of this, your PAR readings could be influenced by specific spectral distributions
not beneficial to coral and skewed towards specific LED ratios.

For instance, lights that use large amounts of Cree Cool White LEDs, which are very intense per watt,
typically have inflated PAR readings but actually have less coral specific PAR than lights running lower power
levels but a higher ratio of royal blue. I've seen this all over the internet and it's used as a marketing weapon.

So, I'm obviously curious as to the actual spectral spread you're measuring and not just going to blindly
accept the photon intensity of a meter without knowing what it's reading. For all I know you're measuring
a large percentage of green light, which cool white LEDs produce in enormous quantities, but has little benefit to coral."

These meters are expensive, but this is what it's all about: http://sunlightsupply.com/p-14301-par-meter-with-integrated-or-remote-sensor.aspx. measures directly from 400 to 700 nanometers. Some will say that this measures the green spectrum between 500 and 600 nanometers, but when you're using it on grow lights, they emit little to no green light so that is a non-issue. Also, measuring at different heights is extremely important. Not just 7 inches away, but 12 inches, and 24 inches as well. The decay of intensity is important to understand. My 2 cents.

ineffablegreen said:

These meters are expensive, but this is what it's all about:
http://sunlightsupply.com/p-14301-par-meter-with-integrated-or-remote-sensor.aspx.
measures directly from 400 to 700 nanometers.

Click to expand...

It's clearly has better response in the blue area, than my meter.
On page 7 there is the conversion table the Sun vs. electric. just like my instrument have.

The PAR meters spectrum response from the link. Page 6
http://sunlightsupply.com/PDF/PARRadiometerIM.PDF




There is also a nice chart over the daily sunlight output in the manual.
(makes me think about the saturation effect, and the talk in the thread "To much light" )

it is simple...hid does beat leds...every time... regardless the algorithm used...which is the only diff tween the par meters and lux/ftc meters

Did you miss something, or what's you comments ?

LED's are the future, HID are good none the less, but when it comes to growing in tents and confined spaces, and when one needs to control noise, LEDS are a better choice over HID any day, But large scale grows do benefit from HID's and also colder climate area would benefit from HID.

Peace to all and keep the happiness growing.

Hey Rasser,
My understanding, when growing with LED the bleaching you can cause is from IR. And PAR meters do not measure IR, IR is above 700 nm, and your PAR meter probably stops measuring around 700 nm. Double check me on that, but that is what I remember, Have you done kill-a-watt readings with your panel? there is a cool page where someone is correlating data, can you email him this info. He dosnt have PAR yet but it would be helpful. http://www.compare-led-grow-lights.com What kind of yield are you getting with that panel so far?
Sidd

cannabuilding said:

LED's are the future, HID are good none the less, but when it comes to growing in tents and confined spaces, and when one needs to control noise, LEDS are a better choice over HID any day, But large scale grows do benefit from HID's and also colder climate area would benefit from HID.

Peace to all and keep the happiness growing.

Click to expand...

The noise coming from the new led lamps like this is really loud, and not great for a closet grow in the same room as you occupy, I have found out.


The noise coming the unit shown in this thread is acceptable after the mods I made.

Siddhartha2 said:

Hey Rasser,
My understanding, when growing with LED the bleaching you can cause is from IR. And PAR meters do not measure IR, IR is above 700 nm, and your PAR meter probably stops measuring around 700 nm. Double check me on that, but that is what I remember, Have you done kill-a-watt readings with your panel? there is a cool page where someone is correlating data, can you email him this info. He dosnt have PAR yet but it would be helpful. http://www.compare-led-grow-lights.com What kind of yield are you getting with that panel so far?
Sidd

Click to expand...

I find that very hard to believe, when looking at the IR output from HPS/MH vs LED shown in the screen-shots
and comparing to the Sun. My 120W has no IR leds and can still course a little bleaching when to close to young leafs.

Yes I have measured the unit with a watt meter and the usage is consistent with the amp's on the labels on the led driver.

I have not completed a grow with the unit shown in this thread, and so far I've only used it to veg with, and the plants grows fast.