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

I agree rasser that some LED panels have some noisey fans, with abit of DIY modding one can control the noise significantly.

Peace to all, and keep the happiness growing.

Hey Rasser what's your feelings on plants under an led(r&b) reaching the "light saturation point" faster than under "white" light(hid/fluoro/sun)????? great thread btw....

PSUAGRO. said:

Hey Rasser what's your feelings on plants under an led(r&b) reaching the "light saturation point" faster than under "white" light(hid/fluoro/sun)????? great thread btw....

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Hey Psuagro, I have no clue as to what makes the leaf saturates faster or slower, or if green light makes the leaf reach that point faster than without it.

Cannabuilding, True, but the temperature is bound to go up, and the new units with many 3W led's in a tiny space is requiring heavy cooling constantly,
and it sounds like 1/2 a vacuum cleaner running.

If one is use to big ventilations systems in the grow room then the noise from the new units should not be a problem,
but for a closet grow in the same room as you occupier, not without earplugs.

Thanks for your honest answer.................can't seem to reach TL/to confirm my feelings.............be safe Rasser and happy growing.......congrats on the win vs holland

Im a bit of a simpleton, but from the first post i read :
the LED with 120w (90w) produced 436 units of light.
the HPS with 250w produced 507 units of light.

my basic maths came up with :
LED : 120w (90w) : 436 light units : 3.63 light/w (4.84 light/w)
HPS : 250w : 507 light units : 2.028 light/w

which means the LED is waaay more light per watt of electricity. Assuming the purchase cost is zero (which we know its not) the LED does better with less and the globes last waaay longer too.
can anyone point out the flaw in my logic?

DaveTheNewbie said:

Im a bit of a simpleton, but from the first post i read :
the LED with 120w (90w) produced 436 units of light.
the HPS with 250w produced 507 units of light.

my basic maths came up with :
LED : 120w (90w) : 436 light units : 3.63 light/w (4.84 light/w)
HPS : 250w : 507 light units : 2.028 light/w

which means the LED is waaay more light per watt of electricity. Assuming the purchase cost is zero (which we know its not) the LED does better with less and the globes last waaay longer too.
can anyone point out the flaw in my logic?

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That's a good way to illustrate the difference, but to be fair to the HPS the number climbed to 700
when i closed the door to enable the important side reflection, and the HPS ballast draws 30W at least,
so it should be 90W vs. 280W and 436 vs. 700.

But the big question is what about the all the green yellow light coming from the HPS, that is making the meters high reading in the sensitivity spectrum chart,
can a plant use all that, I think my par meter is deeply unfair to LED.

NB. If the unit is making my electricity bill decrease by a 1/4 then the unit will have payed
for it self in a year. My modifications have maybe pushed that to 1.5 year ( the price for the added head sinks )
but the unit should last much longer after the mods.

When you pay 40 cents for a kilowatt hour, LED and alternatives in general looks very attractive, I think that's the hole
point of hitting ourself with an serious energy tax, it make alternatives as wind and solar compete on, some would say, an equal non polluting ground.

DaveTheNewbie said:

Im a bit of a simpleton, but from the first post i read :
the LED with 120w (90w) produced 436 units of light.
the HPS with 250w produced 507 units of light.

my basic maths came up with :
LED : 120w (90w) : 436 light units : 3.63 light/w (4.84 light/w)
HPS : 250w : 507 light units : 2.028 light/w

which means the LED is waaay more light per watt of electricity. Assuming the purchase cost is zero (which we know its not) the LED does better with less and the globes last waaay longer too.
can anyone point out the flaw in my logic?

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No flaw with your logic..........but led use in horticulture is still in its infancy IMO and needs more time to evolve into an HID substitute...........
Because of led's narrow spectral output, issues will arise that some species of plants will favor the lights over others (needs to be designed specifically for a certain plant species atm).........manufacturers are alleviating this by adding 12+ wavelenghts(not a solution/just a shotgun method)in their panels and/or adding 2700/5000/6500/10000k white leds(better/but may be losing overall efficiency by adding unusable nm's/ hid?IDK) to make it more versatile.........I personally believe that the future for horticultural led panels will need to be designed from the ground up for a specific plant species and/or have adjustable spectral output like Lumigrow/HGL new omnipanel(hate this company!/ advanced led new xml series......trust me the trend is going towards spectral adjustment/ we are going to see many new panels with this feature soon ..........

Rasser said:

That's a good way to illustrate the difference, but to be fair to the HPS the number climbed to 700 when i closed the door to enable the important side reflection, and the HPS ballast draws 30W at least, so it should be 90W vs. 280W and 436 vs. 700.

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Ok so the simpleton tries again :

LED : 90w : 436 light units : 4.84 light/w
HPS : 280w : 700 light units : 2.5 light/w

when you look at the amount of money that is involved (either selling or for self) a few hundred dollars isnt that much. As you said :

Rasser said:

If the unit is making my electricity bill decrease by a 1/4 then the unit will have payedfor it self in a year.

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when you consider that you buy a new HPS globe every 6 months or whatever and LEDs last 12 years, its a long term bargain. I have 3 x 600w and 1 x 400w HPS lights and ZERO LEDs so im not bias towards them but im always keeping an eye open for new ways.

So can someone explain to me in simpleton language why a LED isnt up to HPS standards yet if you get almost double the light per watt, and its in a more useable form as well?

Im looking at : http://www.ebay.com.au/itm/High-Power-160W-LED-Flood-Light-2-80W-LEDs-6000K-Waterproof-Warranty-/180839974065?pt=AU_Home_Outdoor_Lighting&hash=item2a1ae704b1

its a 160w floodlight with 160w actual used electricity. Its also an outside floodlight so it must have some decent penetration surely? It claims to have 2 x 80w LEDs but that doesnt seem right to me?

This is the 80w LED chip : http://www.ebay.com.au/itm/80W-LED-Chip-4-Ceiling-Flood-light-Spotlight-Wall-Lamp-32V-2400mA-Pure-white-/180765694433?pt=AU_Lighting_Fans&hash=item2a167999e1

That look like a nice silent panel.


But since LED's don't like high temperature I can't see the reason to put so much power so close together
instead of even it out over a larger area. Lamps like this should be a great replacement for industrial lighting
currently using HPS, but as a grow lamp, I think spending the 160 watts on red and blue LEDs is better for plant growth.

isnt the problem that most grow lights are 1w or 3w LEDs and lack penetration?
isnt that a 80w LED and as a outdoor floodlight it should have mass penetration?
thats my question. (well that and why people question LEDs if they are twice as electricity effective)

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.

DaveTheNewbie said:

isnt the problem that most grow lights are 1w or 3w LEDs and lack penetration?

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That's the question I'm trying to visualize. It's clear that using 1000 tiny 5mm LED's
is not energy efficient compared to using 1W and 3W but I can't see any reason why
1000 tiny LEd's should not have the same penetrations as 1 big LED

I'm thinking back to this Youtube video :http://www.youtube.com/watch?v=NkkU0UO3sek
where a guy has build a 500 5mm LED flashlight using 22.000 mcd LED's that are consuming 50W,
it's a funny toy, but I don't think you can say that the light don't penetrate:

I think thats an impressive distance for a 5mm LED

Attention fellow cheap ass LED growers !



I just did a measurement on the difference between the light hitting the PAR meter with or without
the transparent glass plate in front of the meter and it goes from 1300u down to 1140u 12% loss
So if you not already have removed the front glass, then it's time to consider the pros and cons of
keep having it in place.

Thank you for the attention.

I just did a PAR measurement where the seedling was standing with the LED light turned off.

HPS only 210u
HPS+LED 375u
LED only 165u

210HPS vs. 165LED and the plant bends towards the LED like crazy, as if the HPS did not exist.

At what distance are these measurements being taken?

^^ great stuff Rasser......keep it up

puffenuff said:

At what distance are these measurements being taken?

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Must have been 10" from the light, the glass was very close to the PAR meter ~ 1".

Rasser said:

That look like a nice silent panel.


But since LED's don't like high temperature I can't see the reason to put so much power so close together
instead of even it out over a larger area. Lamps like this should be a great replacement for industrial lighting
currently using HPS, but as a grow lamp, I think spending the 160 watts on red and blue LEDs is better for plant growth.

Click to expand...

And I think panels like these are way to much in the opposite direction - to little power distributed over a to large an area.

Rasser said:

I just did a PAR measurement where the seedling was standing with the LED light turned off.

HPS only 210u
HPS+LED 375u
LED only 165u

210HPS vs. 165LED and the plant bends towards the LED like crazy, as if the HPS did not exist.

Click to expand...

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)

"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.