It’s no coincidence, I’m sure, that when someone asks me how many watts of LED they need, I generally say between 35-50w per square foot, depending on the LED. Heh.
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i know this is NO WHERE near as accurate as micromoles per second, but it gets us where we need to be…
up and growing.!!
Since many people appeal to you for lighting advice, I’m sure you have a range of acceptable lights that can work. You’d have no way in reality (unless they flat out told you) to know what the person was willing to spend…or could spend on a light. While some may balk at $500 for a grow light, others may not blink an eye. Its a balancing act to be sure, and I appreciate you telling me the 260 is adequate, but the 320 is a very nice light if you want to spend the extra bucks. I appreciated your approach and advice.
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That’s the answer I expected. I left 420mag and grasscity for exactly those reasons. Not limited to light, but people spouting off information they have no idea about, but read it somewhere on the internet so it had to be true.
I’m not frowning on trying to help, even if it’s with only a portion of the information. But I definitely spend more time here refuting unsubstantiated lighting claims than anything else. I would prefer not having to chase people around making sure members get the right information is all. There’s no reason to be running reasonably driven quantum boards at 40 watts per square foot without controllable co2 supplementation.
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This exact reason is why I’ll use GL and Kurt for this new system I just put in my online cart after talking it over with y’all on ILGM. I know $827 is not retirement income for Kurt, but every happy customer tells other customers and may come back more than once.
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i m using one HLG-120H-54A per 135w V2 board (from GrowersLights), is that adequate/‘reasonable’.?
my set up is not a good comparison, i use glass between the plants and the boards and they r air cooled, i will not post my 44 wpsf without clarifying.!
my flowering plants stay 9"-12" from the boards, i can only do this because of the light chamber moving a lot of air across the boards.!!
i started studying the actual umol, ppf, and ppfd of LED, but quickly realized that without good light measuring equipment, which very few growers have, i do not have, those numbers were just numbers,
no one measures lights the same, even ‘side by side’ comparisons also have many variables,
a simple watts draw meter is obtainable to most growers and is easy to understand without schooling,
most LED companies will provide the actual watts used, might mean an e-mail or 2 but obtainable.
good to know u have tested the QB’s, assuming with plants and meters,
i will adjust my advise to 30-40 wpsf of QB for flower.!!
how does the different strength QB’s compare as far as penetration,
does a 135w QB penetrate the canopy better then a 65w QB.?
with over 40 wpsf can i grow a taller/denser canopy.?
Light penetration isn’t really a function of power level. No matter how many watts you have the light doesn’t shine through leaves right?
You don’t need a light meter at all to calculate light density, provided light output is given. That is half the reason the boards are as popular as they are. Hlg’s numbers are provided and verified by third party laboratories, and when they say whichever model is good for whatever space, it’s based off of multiple university level or higher studies conducted in controlled laboratories. People like us even with a light meter don’t have the control to even bother trying to refute any of it, as you pointed out.
That is true. But there’s no standard to quantify based on power consumption. I think it’s fair to lump just about every blurple panel using epistar leds and a non branded driver into the same category, and what little test data is available supports that. It’s not by accident that they don’t give a total flux, its because nobody would buy them if they did.
There are always exceptions. I talk to @Covertgrower every day. Its impossible to get him to a run a reasonably sized light. I still tell him every time it comes up he’s wasting his money lol. If that’s what he wants, I’m more than happy to get him or anybody else there. Otherwise I stay in line with what the best available data suggests.
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My plants tell me everyday they like my light with lots of side growth and excellent penetration. 
@dbrn32
@SlowOldGuy I’m running a potential of 75 watts per square foot. The fixture is dimmed at the moment, but very capable. As @dbrn32 pointed out, it’s too much wattage for the space, but I like to know that I’m running too much light.
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I’d say. If I had your money I’d throw mine away haha.
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ME TOO.!!! LOL
i had a 2’ x 3.5’ closet with a 400w HPS and a 400w MH in it.!! lol again
it was 114 wpsf powering a ‘SoG’ with 30+ gram main colas from time to time,
the pisser was… the largest colas usually got bud rot and were disposed of, sad day.!
everyone at Overgrow.com said i was insane for having 800w of HID in 7 sq ft.!!
that bud was as good as any outdoor i had ever grown or gotten.!
probably could have reduced to 70-80 wpsf and done just as good, but it is what i had to use.
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i read and try to remember every bit of info u post.!!!
u have extensive LED knowledge and it all sounds solid.!
light shines through healthy leaves, this is why u _can_use a green light during the dark period,
u can not measure this with a lumens/candle power meter, but the plants show it.!!
the light is filtered a little tho, that’s why we get better bud sites not covered by leaf.
indoors leaves r a necessary evil, because the light does not rotate above the plants.!
with HID, the more wpsf i introduced the lower the fluff turned into bud.!!
i only ran 400w HPS for 3 months in my new grow then swapped to QB,
at 44 wpsf of QB (air cooled on glass, 12" above the tops) i have very little to no fluff down 16-18" deep into the ‘canopy’,
from what i see on the net, i know (believe it or not), no fluff in 18" is pretty good…???
100% of my Blurple knowledge is from the net, i have never been ‘sold’ on em,
been seeing Blurple for ~15 yrs, but finally got ‘persuaded’ to try QB.!
like u said earlier, many struggle with price tags…
$600 was A LOT of money for me to spend, but i know the value of good lighting.!
light is plant food.!!
Edit
$600 to fill only 11 square feet of total grow, 5.5 sf of veg and 5.5 sf of flower,
but… a $600 investment to see 15-30 grams per week is well worth it.!
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Are you sure? Because I’m pretty sure everywhere I have seen suggests more that green light specifically is reflected. On top of that, NASA and others have shown plant response to green wavelengths. Its just not really happening at low intensity for short periods of time.
I don’t buy into the theory that 100 watt light shines through leaves more than a 50 watt light of same source. Or that 100 watts of one light source will shine through more leaves than 100 watts of different light source. What I do buy into, is that the more light coverage you have the greater light penetration you will have. I would be more than happy to review any studies that say differently though.
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this is not theory, it is proven with HID lighting,
my 400w HPS is good for an 18" tall canopy, (
from what i have seen on the net) a 1000w HPS can penetrate down to 24",
this has been proven also, commercial growers call it ‘shared lighting’,
the light angles is the biggest advantage to light movers, in my self-educated opinion.
this is why i think my 2x QB’s r out doing the 1x HPS…???
yes, i m 100% positive.!! “light shines thru healthy leaves”.!!
i agree, most of the green is reflected, hence why we see it as green.!
other light spectrums shine thru tho just filtered slightly,
a bud site growing under a fan leaf does good, not great like un-shaded, but good,
if u shade that same site with an impenetrable material, that bud site would suffer.!!
cannabis does respond to green light spectrum, but it also can also easily do without in flower.
cannabis is tuff, it can handle many different light conditions,
u can actually grow a plant germ to jar with incandescent or halogen lights.!!
will it be great…??? HELL NO, but it would soldier thru and finish.! LOL
my best results has been with a rotating crop going into 12/12 under 400w MH and finishing under 400w HPS.
the 2 lights were side by side in 7 sq ft, 114 wpsf, and they went in on the MH side and moved every 2 wks towards the HPS side, finishing under the HPS of course,
this was done with hardware store bulbs, $30 each, no where near as good of a spectrum as the new $20 bulbs from the hydro store.!
it produced perfect shaped, LARGE, some of the best u ever smoked main colas and buds.!!
@dbrn32
i hate to post this, it goes against good advice of “keep your 12 hrs dark”,
they can handle up to full moonlight in flower from time to time and not stress,
very low levels of light does not effect them.
I would love to see a picture of something like a full screen under hps with the floor under the screen illuminated at any distance. I’ve looked a lot, can’t find one. I would also accept whatever study or report that proves this.
That doesn’t support your position. “Good” is subjective, and the fact that its not the same as anything above means it does suffer. That also doesn’t take into account reflected light, or more importantly that it doesn’t need to get any light at all to develop. Plants send energy where they receive it. By your words a plant under a 1000 watt hps lamp could be directly under a handful of fan leaves as long as it’s not further than 18" and get adequate light. Anyone who has seen a flowering plant knows that’s not true.
I’m not aware of anyone saying you couldn’t? They produce some light in the par region right, so why wouldn’t they? Both are poor choices because they are horribly inefficient and the wavelengths emitted and low par levels don’t produce the plant responses indoor growers look for.
Sure, I don’t think anyone would argue with that kind of energy you didn’t do well. It’s also a horribly inefficient way to grow. You would probably just never see it by rotating plants through.
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This is true, there’s virtually no measurable ill intensity which correlates to no plant response.
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ummm, no, that is no where close to what i have posted.!
a single leaf shows little effect, 20 leaves would filter enough light to noticeable amounts.
this is why light movers and ‘shared lighting’ works better then a single bulb source.!
after this i will have to recheck your info.!! u r posting like a new gen member.!!
“good” or any judgement is subjective, but most normal growers would know the difference between good and great.!! LOL
the studies r not there, it is up to growers to wade thru the piles of internet B S.!
LOL, horribly inefficient is an understatement, but the return out weighed the cost, hands down.!
done that for 3+ yrs and the math showed profit.!
It’s also the reason light penetration is a function of coverage, not power. Which is what I said in the first place. What you posted…
Should I go look for the definition of what a plant canopy is, or can we put this to rest?
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i dis-agree, this may depend on what lighting we use…???
with HID, CFL, and T12 floro u get more for more.!
i tried to expand my knowledge but u were unable to answer my questions.!
i would still like to know if more wpsf of QB will penetrate deeper into a canopy, but…
u have obviously not experimented into QB or any other lighting.
man, this sounds like u want a fight…???
i m just sharing many years of growing and monitoring grow sites, NOT looking for a fight.!!
studies and facts r few and far between, experiences and internet r all we have.!
how many years of indoor cannabis grow shooling do u have.?
i have NO schooling, but a few years of experience.!
give us some pics and/or info of your comparison grows.!!!
Hello,
@dbrn32 is educated and very generous with his time toward other growers on this site, Idiot is really not a great word to use toward others.
Always look on the bright side of life and leave aggression on the road behind.
peace from down under
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