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Is my led too close?

Discussion in 'Newbie Central' started by Tokintoucan, Jun 11, 2017.


    NoFucks2Give Well-Known Member

    I have to assume you had very poor uniformity, and you did not measure the PPFD.
    How many got bleached? Not all of them.

    I also forget many of these units do not have dimming circuitry. Where you put the fixture as close as you want then adjust the PPFD to what you want. I have never had a fixture without a dimmer. And I use wide angle OSRAM SSL150 LEDs without optics to get good uniformity at minimal distance between the fixture and canopy. And I have the app that simulates the spacing and height to find the optimum height and spacing.

    I do everything possible to minimize the height. The Inverse Square Law is important. The power can be reduced to 10% (one tenth) when the height is lowered from 19" to 6". Cutting the electric cost 90%.

    A lot of the box type fixtures narrow angle optics that concentrate the slight into a smaller footprint and designed for a higher height. That does not make sense to me. The only reason to do that is to be able to publish a spec with a high PPFD. I did look for optics on the box before. At 400 Wall Watts that unit is not very powerful with epistar LEDs. The uniformity is important as I mention. 6" IF the light spreads across the canopy. If the uniformity sucks and the light is concentrated in one spot, then no it cannot be done.

    I assume you read my diatribe on Watts. Watts doesn't mean Jack Shit! What matters is the intensity of the photons hitting the canopy. When people buy a fixture based on Wall Watts you are only encouraging the vendors to use shitty inefficient power supplies. Buyers need to smarten up. And yes, I know that is not easy. It's a nightmare out there. The is a shit load of things between the wall and the photons exiting the LEDs that can degrade efficiency. Heatsinks and thermal management are expensive. Temperature degrades efficiency enormously. But if you buy on wall watts the vendor can fuck everybody. And that is what they are doing. The use inefficient epistar LEDs, shitty power supplies, and only enough thermal management so the LEDs do not die during the warranty period. And they get to charge more for doing a shitty job because the buyers are uneducated in how to choose a fixture. The most important thing is the amount of radiant flux, the PPFD. Then uniformity. Then the amount of electricity. Then the cost. A dimmer is a very good feature.

    You must also understand the "Reviews" are paid advertisements. Likely everyone of them.
    Last edited: Jun 16, 2017

    Budzbuddha Well-Known Member

    18" .... Both switches on ..... Plants happy

    KRSTEK likes this.

    NoFucks2Give Well-Known Member

    If that was aimed at me, fuck off, that would make you clueless. It's my fuckin' job.

    NoFucks2Give Well-Known Member

    That is not true. You just need to buy better fixtures. And do better at buying fixtures.

    NanoGadget Well-Known Member

    Actually my uniformity was decent. The problem was the system I had cobbled together to hang/adjust the height of the light malfunctioned and I didn't catch it right away. Obviously the bleaching was most intense in the center where the PAR is highest, but it affected damn near the whole canopy. Also, even though it's an older light (in terms of LED systems) it does use OSRAM SSL emitters.
    KRSTEK likes this.

    NoFucks2Give Well-Known Member

    Probably the SSL80s. When the height is getting close to the canopy inches in height increases power logarithmicly. 50% reduction in height is a 4x (400%) reduction in required power.

    If you have a PAR meter, uniformity, and dimming, you can significantly reduce the electric.
    The box fixtures have to cram in the LEDs. Ideally LEDs would be spread out for uniformity and allowing the fixture to be close to the canopy but those metal core PCBs are expensive. Everybody accepts that obstacle and deals with it. I don't accept it. I found a solution. Look for the problems and solve them. Nothing is impossible until someone does it.

    HydoDan Well-Known Member

    No you FUCK YOURSELF!!! Just added to my ignore list.. Nothing to learn from you ass wipe!! You have posted no pics and have no real growing experience .. just a bunch of googled info.. what a dumb fuck!!!
    KRSTEK likes this.

    HydoDan Well-Known Member

    Fuck you.. been growing for close to 50 years.. You know nothing dumb fuck!!
    KRSTEK likes this.
    Lip G.

    Lip G. Member

    I second that ... indeed the cat looking for advice was going to fry his plants .. I use the Spectra 450 and with both Veg and Flower turned on, I keep it at about 24" .. and to me that seems to be plenty close enough .. I"ve seen enough around here to believe light burn is real, and does happen with LED's .. the buds I am about to harvest in a week are "textbook" beauties .. only in my wildest streatch of the imagination, would I have dreamed buds the size of my fist are grwoing under my 450 LED in a 3' x 3' x 5' tent.

    Instead of seeing how close you can get them, what I have just found to be successful, is getting a light meter and see where the optimal coverage hits the canopy. My plant doesn't want any more than what I"m giving her.

    My end product, is exactly what the expert who sells me my supplies, advised. I do as he says, and everything turns up golden.

    On my next grow I will try to master preventing the streatch in early to mid veg - Something I haven't done yet with the Viparspectra 450 - i used a spiral cfl that seemed to work well, but I'll check on using the LED this time around.

    Problem with LED burn is that you don't see it till after it's too late ... when I see the gorgeous buds under my light, I would'd even dream of lowering my lights in fear of burning off resins, turpines etc ets .. once it's burnt .. you cannot unburn it.

    Your veg looks amazing btw .. google what light burn and wind burn looks like .. then google a chart for plaint ailments according to leaf symptoms. The charts are all over the web.

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