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

squarefodder

Active Member
I just made a small test without know it.

Right now in my closet there is a 250W HPS running in one end,
illuminating 3 mature ladies and in the other my 120W LED light vegging 4 plants.

I place a 2 day old seedling right in the middle of the two lights
looking at the dirt and plant with my eyes, it looks like to illuminated the most from the HPS.

But if I take a picture of it, the flickering from the 50Hz HPS light is visible and is messing with the picture,
to the human eyes the dirt and the hand is yellow.



The plant sure knows witch way to go, it's not fooled by the human eyes :-)




That should make a interesting test when using my par meter
500umol LED and 500umol HPS witch way do the seedling go
I think I know the answer but I could use it as a measuring device.

250u LED vs 500u HPS if the seedling still goes towards the LED
then we have a clue as to what the PAR meter conversion factor could be.
Nice work Rasser. I have some clones that are on the edge of a 400w hps and 128w (actual draw) led light. I just put them there, it will be interesting to see what light they turn towards. I also have a stretchy plant that is on the edge of a blackstar 240 and 400w hps. Ill look in the morning and see what phototropic response its giving.
 

Rasser

Active Member
Fascinating. So all the science points LED, and yet people scream how much they suck. Doesnt add up.
I can only put it down to starting with such low lumen output (per LED) means that the light weakens to something useless too quickly (aka no penetration).
But if the actual LEDs themselves were bigger and more powerful this wouldnt be a problem (instead of mounting masses of low power LEDs)
First I think that the LED grow light business started out as a novelty thing with these 14W panels with 5mm LEDs
and then moved up to 90W ufo's that started the claim that they where equal to 600W HPS.

Right now I can still see a local site claiming a 50W UFO can cover 18m2 and have a picture like this next to it:


Then we got the outrageous power difference that is confusing people.

Then we got the impossible grow conditions - I've seen one guy trying to grow with LED
at a temperature of 50°F and wondered why there was slow growth.

Then we got the lack of experience in using the panels correctly for optimum growth

And combined with the high startup cost, short memory
(some people talk as if the cost of a bulb is all the matters and the cost of running that bulb for a year is irrelevant),
and the low electricity cost in the US

HPS is still looking good to some people.
 

Rasser

Active Member
"Penetration" is a vague/incorrect term IMHO
Light is measured in lumen (or radiant flux) and 10 pcs 100-lumen LEDs will produce as much light as 1 pc 1000-lumen LED. If they are all focused towards the same point, there won't be any difference whatsoever.

The only difference lies in efficacy and smaller LEDs seem to outperform the bigger LEDs in pure terms of lumen|radiant output per watt.
But you have to admit it's sexy as hell, all this penetration and now we also got diamond shapes I'm blushing.
and charts to see how deep our particularly penetration is.[link]
 

DaveTheNewbie

Well-Known Member
"Penetration" is a vague/incorrect term IMHO
Light is measured in lumen (or radiant flux) and 10 pcs 100-lumen LEDs will produce as much light as 1 pc 1000-lumen LED. If they are all focused towards the same point, there won't be any difference whatsoever.

The only difference lies in efficacy and smaller LEDs seem to outperform the bigger LEDs in pure terms of lumen|radiant output per watt.
IF this is true then why are the 3w LEDs considered better than the 1W LEDs that are better again than the smaller again LEDs?

Theres a law somewhere that states that the light intensity halves over a distance of X. So at distance of X it is half of what was produced, at 2x its a 1/4 and at 3x its 1/8, etc.
Thats why a 600w one source HPS travels longer distances with an effective intensity than LEDs, even if there are 600w worth of tiny ones.
My limited simpleton knowledge calls false on this sorry. This is why i would be more interested in a single 80w LED than a mass of tiny 1/4w LEDS that add up to 80w.
 

resinousflowers

Well-Known Member
hps will out perform leds in flowering everytime.
leds are good for vegging tho.
ive seen many side by side comparison grows,and that will always tell you alot more than a light meter,coz the bottom line is its about the results you get using those lights growing,its not really about the results you get from a light meter.
 
Have you ever grown with LEDs? How were your results compared to your normal HPS results?

hps will out perform leds in flowering everytime.
leds are good for vegging tho.
ive seen many side by side comparison grows,and that will always tell you alot more than a light meter,coz the bottom line is its about the results you get using those lights growing,its not really about the results you get from a light meter.
 

DaveTheNewbie

Well-Known Member
hps will out perform leds in flowering everytime.
leds are good for vegging tho.
ive seen many side by side comparison grows,and that will always tell you alot more than a light meter,coz the bottom line is its about the results you get using those lights growing,its not really about the results you get from a light meter.
everyone "knows" this, everyone parrots it.
Ive only ever growed with 3 x 600w HPS, so i know it too.
I want to understand the technology, not pass judgement on it
 

Rasser

Active Member
IF this is true then why are the 3w LEDs considered better than the 1W LEDs that are better again than the smaller again LEDs?

Theres a law somewhere that states that the light intensity halves over a distance of X. So at distance of X it is half of what was produced, at 2x its a 1/4 and at 3x its 1/8, etc.
Thats why a 600w one source HPS travels longer distances with an effective intensity than LEDs, even if there are 600w worth of tiny ones.
My limited simpleton knowledge calls false on this sorry. This is why i would be more interested in a single 80w LED than a mass of tiny 1/4w LEDS that add up to 80w.

I see the difference in the light source output like this.

If you want to get a tan from sunlight it doesn't matter if you are on the rooftop of a tall building
or down on street level, the distance between the two is insignificant compared to the distance to
the Sun and the output coming from it.

So you got a trillion billion mega watts coming from far away. (it has to be or everything would get burned)

But a solarium can give you the same tan using only 1Kw, but you have to be close to it,
and if you move just a short distance away from it it totally looses it's power to give you a tan.

So we got a choice of using a single high power point source far way
or using many smaller ones very close by, the plant can't tell the difference
if the light is coming either.

What's is wrong with these 14 watt panels with 5mm LED's is that they are not complete full
of LED's shoulder to shoulder like the 500 led flashlight.

Using 1 and 3 watt LEDs make sense compared to using thousands of 5mm witch require a big pcb's and manual labor.

optics lenses like a looking glass also illustrates the difference, the more you focus the beam the hotter it gets, but the coverage area is also shrinking.

So in the vegetative phase we want 120° lens optics so the lamp can get close to the plants and 60° lenses during flowing when the plant is tall
and there is a long way to the bottom leads and buds.

Non of the lamps we are buying are great for a start to finish run, getting two kinds of optics make sense like cold and warm CFL bulbs
for each phase. They either put out to much in the beginning, and waisting energy or have to little in the end.
I think using different kinds of lights and switching them on as the growth goes along is preferred.

It's visible in my closet right now, the 4 young girls have outgrown the 120W led lamp in width
and it's time to either raise the lamp to cover all the leafs, but then the intensity will drop to below that of Sunshine.
so more lamp is needed, if I want to keep vegging with Sunshine levels of light.
When the plants gets tall then it's time for the 60° optics for the penetration to the bottom.
 

Rasser

Active Member
And combined with the high startup cost, short memory(some people talk as if the cost of a bulb is all the matters and the cost of running that bulb for a year is irrelevant),
and the low electricity cost in the US. HPS is still looking good to some people.
I just tried this danish energy savings calculator, to see the difference starting a grow from 400W HPS vs 250W LED
(I'm assuming that 250W actual draw can replace a 400W hps)
I'm sure there is one for every country somewhere on the net.

And it looks like if you are expecting to stay alive for a couple of years then LED is the way forward.
After one year the unit has payed for it self, two years and the savings start coming in.

Edit: 1000 KR = 188$ = 107£

 

PSUAGRO.

Well-Known Member
Hey Rasser......great info as always............I really like your idea of an udjustable lens angles on a panel/brilliant..........reminds of those gavita adjust-a-wing reflectors.......I think that might be the next step............120 degree during veg and 60-90degree during flower...killer:)
 

puffenuff

Well-Known Member
Hey Rasser......great info as always............I really like your idea of an udjustable lens angles on a panel/brilliant..........reminds of those gavita adjust-a-wing reflectors.......I think that might be the next step............120 degree during veg and 60-90degree during flower...killer:)
apache tech already does the different optics angles on the same unit - standard at 14degrees and if you crack open the case you change some screws and make it 50degrees.
 

patrikantonius

Active Member
IF this is true then why are the 3w LEDs considered better than the 1W LEDs that are better again than the smaller again LEDs?

Theres a law somewhere that states that the light intensity halves over a distance of X. So at distance of X it is half of what was produced, at 2x its a 1/4 and at 3x its 1/8, etc.
Thats why a 600w one source HPS travels longer distances with an effective intensity than LEDs, even if there are 600w worth of tiny ones.
My limited simpleton knowledge calls false on this sorry. This is why i would be more interested in a single 80w LED than a mass of tiny 1/4w LEDS that add up to 80w.
Considered better by whom ? Those who sell them ? ;)
The intensity of light decreases because of dispersion and this is related to the angle of the light rays (-> lens). Light losses due to travelling in the air are almost nonexistent.
 

squarefodder

Active Member
here are some clones sitting under a 80w actual draw led and also on the edge of a 400w hps.

IMAG1460.jpgIMAG1461.jpg

They are not leading towards the hps that's for sure.
 

Rasser

Active Member
I was measuring the output from a E27 3x1W(4W actual/1W driver loss)
warm white LED spot at 3-4 inches away there is about 1500uMol in the center, so i thought why not do a micro veg



After a few minutes the plant raises the leafs, don't know for sure if that's a sign of joy(live concert hands in the air)
or a emergency (help I'm drowning) kind of a signal, I'm inclined to go with joy for lack of water is the opposite direction :-)
EDIT: Or else I'll have to change avatar.



Talk about directional lighting.
 

Rasser

Active Member
I've always looked at the plant stretching for the light as a positive, but I'm wondering in this case if it stretches that way because it's a blue based LED and plants stretch/lean towards blue light.

http://www.photobiology.info/Christie.html
Good link thanks !
And the seedling did have line of sight to two rows of blue LED's.

Blue Light And Phototropism
Unlike humans, plants are immobile, and at the mercy of their surrounding environment.
Consequently, they have evolved sophisticated mechanisms that enable them to perceive
and respond to environmental changes, and to modify their growth accordingly.

Some of these processes actually involve movement. Not movement of the plant itself,
but movement of various parts of the plant. One example is phototropism,
a Greek term describing the process by which plants grow towards light.

As early as 1880, Charles Darwin had noted: "no one can look at the plants growing
on a bank or on the borders of a thick wood, and doubt that the young stems and
leaves place themselves so that the leaves may be well illuminated" (1).
Phototropism is especially important for germinating seedlings, whereby the emerging shoot
must grow towards the light to survive by maximizing the capture of light for photosynthesis (Figure 1).

In 1887, the German botanist Julius von Sachs was the first to examine whether phototropism
could be stimulated by particular colors of light (2). By using both colored glass and solutions to
illuminate plants with different wavelengths of light, Sachs found that blue light was the most effective.



Figure 1. Time-lapse image series showing the phototropism response of an oat seedling.
After 3 days of growth in the dark, the oat seedling was exposed to dim blue light from the left hand side for 9 hours.
Pictures were taken at various intervals.
 

Rasser

Active Member
Hey Rasser......great info as always............I really like your idea of an udjustable lens angles on a panel/brilliant..........reminds of those gavita adjust-a-wing reflectors.......I think that might be the next step............120 degree during veg and 60-90degree during flower...killer:)
Thanks.

I'm trying too visualize what a optimal even canopy center intensity - directly on top of the plant - DIY grow light should look like.

120° -60° -30° lenses and slanted some degrees maybe.

Mounting a flat plate on a curved surface for heat distribution is not good, so the heatsink
in this illustration is properly very difficult to make. And the angles used in the triangles are not 100% correct.



Click for pdf


It would be fun if the grow light had barn doors on them, and instead of black, it should be four mirrors.


I think It would have done wonders on this UFO

 
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