Discussion in 'Indoor Growing' started by Mr.Buds, May 8, 2008.


    Mr.Buds Well-Known Member

    can anyone just lay it down for on how lumens functions with marijuana and what I should be doing to make sure that my plants get enough lumens needed.

    raeman1990 Well-Known Member

    lumens =l ight intensity

    more = better

    3,000 per square foot for veg

    10,000 per square foot flowering

    those are the ideal outputs

    koncyse Well-Known Member

    you also want high range kelvins around 5700-6000 for veg (spring and summer is some bright shit) and around 3000 for flower (fall is some red colored shit)

    drumbum3218 Well-Known Member

    More lumens per watt (lumens/watt) means faster growth during veg. stage and ultimately bigger, fuller buds during the flowering stage. For Flowering you need lights that are rated at 2700 Kelvin or 2700K. For you need lights between 5000k and 7000K. I think the standard, or rule of thumb, is 30 watts for every square foot of grow space.

    drumbum3218 Well-Known Member

    If you are using cfl's u want more small lights rather than one big one. Smaller wattage cfl's put out more initial lumens per watt. So ten 23 watt lights at 1,700 initial lumens each (17,000Lumens/230watts = 73.0 L/w), would be a lot better than one 250 watt cfl that only puts out only 16,000 lumens which is only 64 lumens per watt. That is 1000 more lumens, and you could probably buy those ten 23 watt cfl's for less money than the 250w cfl.

    koncyse Well-Known Member

    if you are using cfl's you should have a shit load because the light wont penetrate as well if i've read up properly... cfl's you want a few angled on top and some on the sides/bottom all reflected toward the plant... you are trying to replicate the sun so keep that in mind..

    regrets Well-Known Member

    I understand you are using the word "ideal" but that means that a 5x5 grow area during flowering would need 250,000 lumens a 1000w hps typically only gives off about 140,000 lumens and I think you would be hard pressed to find anyone using more than 1000w hps in an area this size, and your suggesting almost double. 3k for vegging seems about right that is about perfect for a 400w in a 4x4. Keep in mind though that this is in the ideal situation and most people are not going to be able to replicate this in smaller indoor grow spaces. My best advice is to use your judgement, and understand that the more light you use (assuming you can keep the temps under control) the better your ladies will do. Good luck with the rest of your research and your grow.
    Pedro Mello

    Pedro Mello Member

    So if I'm using a 480W driver should I divide that by 30 to find the ideal area?
    Or is it 30w/ft² only of "useful" wattage (considering the efficiency)?

    GBAUTO Well-Known Member

    Hello, Pedro.
    Nothing like reviving a 10-year-old thread.
    You are correct on both questions. What I believe we are trying to determine is how 'much' light we need to get to the intensities to grow some dank. Using power levels will allow you to calculate how much light if you know how efficient the source is at converting electricity into photons. Most HID and older leds will need approx 50w/ sq ft but as you get into current tech leds the power level can be dropped down to 30-35w/ sq ft because of the increased efficiency.
    Pedro Mello

    Pedro Mello Member

    nice!!! got it.

    so if I have a 480w driver with 50% efficiency, I should build a tent with (480*0,5)/30 = 8 sq ft (using leds)

    how bad would be 25w/sq ft?
    1212ham likes this.

    TacoMac Well-Known Member

    It's 50.

    GBAUTO Well-Known Member

    The most accurate method would be knowing the PAR output of the light. It's measured in micro moles(umole) of photons. Then you could use that number to see how much area it will effectively illuminate. PPFD(density) uses square meters for area. Anything over 600 PPFD is ok.
    Pedro Mello and 1212ham like this.

    1212ham Well-Known Member

    It would be smoke'n hot at 50% efficiency. Meanwell HLG drivers are around 89-94% depending on the exact model and operating voltage. About 3% better on 240Volts as I recall. Tell use the LED you plan to use and we can give more specific advice. Also, I suggest posting in the LED section.

    1212ham Well-Known Member

    @ GBAUTO is right on the money, 30w/ft. gets it done with good, efficient LED. These days that's about 150-180 lumen per watt. White light is where it's at, COBs, strips and boards. In a year or two it'll be 25w/ft. (:
    churchhaze likes this.

    TacoMac Well-Known Member

    You are delusional.

    According to your "pulled it out of your ass" figures, your 30 watt per square foot light would be 40% more efficient than a MH/HPS fixture.

    That doesn't exist on this planet. Not even fucking close. Even the VERY high end COBS are only 15 to 18% more efficient on a good day. Some brag about them being 20% more efficient, but that's about the limit of it.

    What's more, according to you, your 30 watts would be producing 5,400 lumens.

    Now, one of the better COB lights out there is a Timber Model 4vs. It uses Vero29 Gen 7 COB LED's. 4 of them to be exact. They each produce 12,500 lumens.

    So, if you do the math on a 3 x 3 foot grow area, the Timber models stats are:
    • 44.4 watts per square foot
    • 5,555 lumens per square foot.
    So please tell us all what magical LED you use that is somehow nearly twice as efficient as one of the best in the world.

    What's more, let's do the math on a comparable MH/HPS lamp which would be a 600 watt fixture in that same area. Then your numbers look like this:
    • 66.6 watts per square foot
    • 6,666 lumens per square foot veg (MH)
    • 10,000 lumens per square foot flower (HPS)
    So is there a power savings on the LED in that same area? Absolutely.
    Will the LED grow as effectively as the MH/HPS? Sure. Both will do a fine job.

    But if you think for one minute 30 watts per square foot is going to come even REMOTELY close to either one of those setups, you are beyond stupid.

    Stop making shit up, pulling figures out of your ass, and spreading false information.

    1212ham Well-Known Member


    booms111 Well-Known Member

    Just ran two 324 boards at 320 watts total in a 5 x 2.5 and it outperformed yield wise by a touch over a 600hps in same tent. Was first time using QBs. With that said I'm not tearing down my 1ks for LED anytime soon, I still prefer hps over LED grown bud when it comes down to final product.
    1212ham and hotrodharley like this.

    TacoMac Well-Known Member

    Here's your problem:

    The light bulb you selected was rated at 5000k, 1.12 amps @ 46 volts for 51.52 watts.

    The kit you selected is only available in 3000 or 4000k. So there goes about 20% of your lumens right off the top.

    Then, your kit @ 46 volts that the bulb is rated at only utilizes .5 amps, so that means the bulb is only going to be getting 23 watts of power.

    Therefore, your so-called miracle fixture is only going to look like this:
    • 20.44 watts per square foot
    • 3,700 lumens per square foot.
    Good luck with that.

    1212ham Well-Known Member

    Not a problem for me! The links I posted are some of the best and most popular LED. But you knew that, right?

    1) It's not a light bulb! :roll::roll: If you were up to speed on LED lighting, you'd know that's a Samsung F-series strip, very popular due to it's high efficiency and efficacy.

    2) "there goes about 20% of your lumens right off the top" Really? Were do they go? Is Samsung falsifying the data? BTW, that kit is called a Quantum Board, made by Samsung for HLG. It's the new version 2, now with Samsung's LM301B diodes. They are among the most efficient lights, and also very popular.

    3) Nice try, that kit is not rated at 46 volts. As anyone can see, the chart has six lines. Apparently you couldn't see the other five lines and quoted approximations of just the first line. What the chart does show is six different drive currents and the corresponding voltage, power, lumen, and efficiency.

    Here's the chart, so you can see the other five lines. :P

    Screen Shot 08-16-18 at 06.11 PM - Copy.PNG

    4) WTF? I can only wonder how you came up with that, maybe you are the one that's beyond stupid, making shit up, pulling figures out of your ass, and spreading false information. I'd like to see your math to calculate watts/foot without knowing the total wattage and area covered!
    Well, not really, I'm sure it would just be more nonsensical, incoherent techno-babel.
    This is how it's done.... watts per square foot = total watts / total square feet. Have a nice day.

    To anyone interested LED, some good links. Some very knowledgeable people there!

    Some good lights.
    Moflow, Fawkes420 and GBAUTO like this.

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