That’s very interesting, especially about the fish lights that change spectrum throughout the day. I imagine we’ll be there in a few short years with the way LED tech is going.
What intensity would ‘average’ sunlight be in lux?
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This is dependent on where and when it is measured, however about 120, 000 lux is the maximum… but for practical purposes 100, 000 lux is probably closer to the reality. This is the maximum value I typically will aim at when building a light… However this is just me and there are likely many others who would use higher or even lower values…
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Cool, thanks. Do you know where I can find info re various lights and their lux output/intensity? Do you think the chart in the first post is roughly accurate as a general guideline?
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Curious,…Does anybody know the average lumen output of an led setup?? I know my Hortilux 1000 hps is rated at 145,000 lumens.
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Well most half decent grow light manufactures will publish this as part of their marketing…
Being in a metric part of the world foot candles are odd measurement for me, but a foot candle basically translates to about 10.764 lux. Which is also not a great unit to measure, however when combined with the relative spectrum distribution chart provide enough information for the average closet grower to make an informed decision… Hardcore growers and commercial large scale operations where every dollar spent has to be measured against every dollar recouped will use PAR and measure in umol/m^2 per sec. as @Northern_Loki has indicated.
If you are looking at building a light, any manufacturer worth their salt will publish a sheet that should contain the information you are after, as well as the relative spectral distribution, CRI, lumens/W across various temp ranges and also the photo-metric web i.e. the “shape” of the light output etc…
DIgikey and other suppliers usually have a direct link to these data sheets and some manufactures like Cree and Bridgleux also have free software tools that allow you to vary running parameters and simulate the results.
Here is the cree example that I took the graph from…
This is a bit of a “how big is a boat” question in some ways… I tend to use longer strips so that my lights rig covers the entire area of the tent and as I say I target 100, 000 lumens ish per square meter. However comparing them is a little like comparing apples and oranges because it doesn’t take into account the radiant intensity nor heat… so given that the inverse square law for light decay applies to all light sources… 145K lumens ends up being significant less when you take into account the distance you need to put the light to prevent it from frying everything… The chart in the first post indicates closer to 60K lumens for a 140K HPS by the time you have got the correct distance!
whereas the led strip lights can sit less than an inch from the canopy… And also scattered light sources are more effectively utilized by the plant vs intense point light sources… so it’s a little complicated huh? Lol
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Thanks alot, this is starting to make some sense to me! I’m really old school about light placement, ie my philosophy has always been ‘as close as possible always’ lol. I think I’ve been causing my plants undue stress and actually making things worse by doing this.
Seeing the same cutting I ran indoors be completely different and much healthier outside is really making me rethink my whole outlook on this, but good, accurate information is hard to find…similar to most things in the weed world.
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No probs dude.
Yeah there is no substitute for that 1,989,000,000,000,000,000,000,000,000,000 kg nuclear furnace in the sky 
Also environment has a massive impact on pheno expression… As you point out, even clones can end up looking like completely different plants!
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Definitely, I’ve never seen it so drastic before though. It’s lead me to believe I still have alot of dialing in to do on my indoor environment.
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This dude breaks down cannabis lighting and several other related aspects like a straight up college professor. Minus his comment about light color not mattering much in there studies being wrong imo. He grows hemp for the studies which dose not produce the same levels of the terpenes and cannabinoids were after so he would see minimal difference. Other then that alot of good info here.
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Beacher, not sure if you had sufficient advice but here’s my 2 cents… Your chart is outdated.
1- If you can comfortably hold hour hand at the colas, good.
2- I’ve seen rooms with 10 1000w HPS and 100+ plants produce well over 10#. The lights were fixed too the ceiling and never moved. 8’. Tasty herb.
3- Outdoor imo will always produce better herb in all factors. What’s indoor? A terrarium… Nothing beats the real thing.
Good luck, grow well.
-Pool
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Sweet link I’m going to eat scrambled eggs and watch it now lol. Thanks
@Poolio yes it always amazes me how far away some people keep their lights and still have great results. We used to stick clip fans onto the shades of 1000w bulbs and keep them like a foot from the tops…if only we knew how unnecessary that was
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To be honest I still agree with the standardish 6"-20" above colas(temp readout below 80F), but it boils down to productivity. Daily too weekly I use to raise my lights, check ph levels on all counts, individually neem oil fan leaves(bad summer once, nip it in the butt before it begins), etc… 10-20 flowering plants. Results were great but what I’m getting at is if you’re doing a micro grow, test all methods as minute as possible. Bigger grows, go with diaries/info you learn from here and other such sites.
Cannabis is life, it always finds a way(yep, Jurassic Park)
Good luck, grow well
-Pool
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If your running air hoods there is no limits.
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True you can ram buds right against the glass with cool tubes. Some people claim they have a small light loss from the glass, but I’d say the intensity of having them closer would more than make up for it.
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I can put my hand on mine, I’m just using 4" in- lines from Menards.
One per hood.
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That’s sweet. It makes me wonder if ‘light bleaching’ is caused by the light itself or just the heat.
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That number seems a bit high (more than double of what the sun is usually when it’s high in the sky with no cloud coverage). The sun on a clear day should be around 2000ppfd or 108 000 lux. Probably less when it’s not summer in some parts of the world. I would take those numbers from a phone app with a grain of salt.
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ya i dont trust the accuracy of the phone apps either, but they are useful for comparison purposes. i think were at around 0 lux here in canada today lol
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Snow for the next 4 or so months, we are shit outta lux 
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