Just a couple of Questions

Lighting…Watts vs lumens? Which is more important?

Recently spotted 1 or 2 gnats in my tent. Something i should worry about?

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yes worry! how much u watering and are you letting them completly dry out.you should! i lost basicly my whole gro to tjem i wattered toooo much.take from my loss natts only show up cuz its way to wet …dont make my mistake or youll have this! my last surviver.best of luck🍀20180329_200946|375x500

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Lets tag in @dbrn32 for your lighting question as I feel I am not the best at understanding lighting
The nats? Are you sure they are nats? They could be spring tails root aphids or other things.
If it is indeed nats you are likely over watering
Let the soil dry out a bit and someone I think @Hogmaster was saying yesterday that putting a couple handfuls of perlite will help dry out and prevent the nats from laying eggs in the dirt.
Hope this helps


And fans and depending on the light that will kill them also at least my hps lec will leds not so much

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Lumens is what I shoot for, minimum 2000 L per square foot, 2x2 tent would be 8000 L. Just my 2cents.


While we’re waiting for @dbrn32 to weigh in I thought I would tackle a bit of the complexity surrounding lighting.

First off: most LED sellers are lying to you. NEVER trust the stated wattage i.e. “1,000 watt LED”. In actuality the output is probably around 250 watts and obviously would screw up a grower’s calculations on needed light based on that alone.

What is more important is lumens on the plant, but more importantly are they the CORRECT spectrum? PAR (photosynthetically active radiation) is a better measurement which you won’t find with most of these lights.

So, Caveat Emptor!

Fungus gnats are a sign of over watering. It would be smart to change your watering practices before something bad happens.


6500 for veg and 2700 for flower, if your growing auto’s the 2700 L will work just fine for a indoor grow because they don’t veg long. 🖒

Thanks for tag gents!

I agree, neither watts nor lumens are ideal. Lumens are better than watts because at least it signifies a light output. But it’s a photometric measurement weighted to green wavelengths because that’s what our eyes identify the best. Plants care about radiometric energy, and in wavelengths they use best for photosynthesis. So photosynthetically active radiation levels are best measure to use.

If you’re using lumens, make sure light spectrum of two lights you’re comparing are the same. I have two leds sitting on my bench right now. One is 3000k 80cri that’s 175 lumens per watt and cost $4. The other is 3000k 90cri that’s about 130 lumens per watt and costs $40. Just because one has higher photometric efficacy, the radiometric efficacy is about the same. And the 90cri spectrum targets more photo red, so a better choice in my opinion.


I agree a little, but this is kind of old school based on old tech.

With high cri offerings more and more available, it wouldn’t be out of touch to think a 4000k high cut could stay competitive or even possibly outflower something like the typical 2700k 70 cri stuff. Plenty of solid seed to harvest grows even under the 3000-4000k 80 cri offerings.


I keep forgetting that you built your own fixtures I need to remember that for lighting qs

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what would you use for a 2x3x3 grow box? would you new technology in led lighting or something like cfl lighting.

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I’m a total led nerd, so definitely them.

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I’d think of lumens, not watts. This is also good to compare different light setups (for example HID and CFLs).
If you have a lux meter these numbers are a good guide : Vegetative: 35,000 - 70,000 lux; flowering: 55,000 - 85,000 lux

What are the odds we could post up some links of some good bulbs? Or are they listed somwhere else?

Until you realise that unless you have a lux meter calibrated for LED’s then the reading will not be “true” as LED lux meters are not the same as those for incandescent/HID lighting, the way they are calibrated are completely different so, at best, you get rough guesstimate of levels and nothing more.

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Lux meters stink with blurple LEDs, because they respond more in the yellow (which is missing). They are not too bad for white COBs. I’ve actually done some experiments with my known spectrum COBs, my cheapo LUX meter, and some color filters. The important thing is to know your lights spectrum is decent. Then you can use your LUX meter to adjust the plant-to-light distance or compare performance with and without reflectors, etc.

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And, importantly, don’t waste time with lux meter apps on phones, they are a complete waste of time without a proper meter to calibrate them and if you have the meter, which isn’t really that expensive, then why waste time with an app?

Ja, lux meter readings are not reliable when LEDs’ the case, but since the question was general I tried to provide a general answer and shoot those numbers just as a guide, many people sitll use CFL and HIDs.

Don’t get me wrong, they’re a good indication but it has to be remembered that they are just an indication and not an accurate figure as far as led goes.

I spent ages looking to see if there is a conversation factor that could give a more accurate figure, but haven’t had any luck there so far.

so would a viparspectra 450 watt led do the job on a 2x3x3 box, i was leaning towards cfl lights but i will do anything to save $$. i know i have to LST the hell out of what i grow because it is a small space. i am still new to this and there is a lot to learn.