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LED light burn


Budwizer
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In the spirit of sharing experiences, Here’s a pic of what LED light burn looks like.

I have done a lot of research regarding how many umols I should be covering my canopy with. Firstly, it’s very seldom you find growers with the instruments to back up what they’re saying. A distance figure means little when everyone is using different lights. Even the manufacturers distance rating goes out the window when you’re using more, or less lights. 

The best info I’ve found, stated 700umol/m2/s as the golden number for LED. This one plant in my current run got a little more than that for about a week. 

So, I’ve raised my lights a little and getting an even 600umol/m2/s now. Based on my experience and measurements, I’d recommend 600 as the upper limit for full spectrum LED without CO2.

523B8EE5-305F-4EFA-909A-0818538C93A7.jpeg

8DBB8999-54C3-4912-AB0E-6F5EC4044EC2.jpeg

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So, turns out my light meter sensor is not cosine corrected. My meter is reading low. Cosine correction is not linear, so one cannot just add, say 20%, but it’s what I have until I can hunt down a formula for cosine correction. My guesstimate is that the above plants were actually seeing around 900 umol.

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  On 5/11/2019 at 10:33 AM, iGrow said:

I’ve been using multiple 65W HLG grow lights and getting 800PPFD when hung 15cm from the canopy with no burn. How close were your lights to get that and do you know the resultant PPFD? 

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You've measured this with a quantum sensor or just thumb sucking this value?

Edited by greenkush
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I’m really curious as to how LED burn works,  I’m hanging my lights at 15cm which seems way closer than advised, but the temperature is fine and my readings say 800 directly under them... so it should be fine/ideal? 

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I’d love to hire/lend it out. Just nervous about guys damaging/not returning it etc. If anyone has suggestions, I’ve tested the hell out of my grow area already. 

I find with lighting everyone has a theory and nobody does the testing. 

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I spent 6-7k on the sensor, with friends. I have other uses for it, checking ‘cold’ spots in my other grows. 

I do DIY and have multiple SMD and COB setups that I test.  Like I said, everyone just wants to sell their gear without the test results. I MUST know, there are too many variables... Haha

B0BC2883-D5CB-4508-B33C-5E53FB83BE56.jpeg

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  On 5/13/2019 at 7:27 AM, iGrow said:

I spent 6-7k on the sensor, with friends. I have other uses for it, checking ‘cold’ spots in my other grows. 

I do DIY and have multiple SMD and COB setups that I test.  Like I said, everyone just wants to sell their gear without the test results. I MUST know, there are too many variables... Haha

B0BC2883-D5CB-4508-B33C-5E53FB83BE56.jpeg

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Cool, yeah i'm busy designing my own lightning system, hence my reason I got one. I also built my own color spectrometer that allows me to check the wavelengths. It seems relatively accurate if I compare it to a friends 25k one. 

Edited by greenkush
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  On 5/13/2019 at 8:34 AM, iGrow said:

@Trailblazer420 I do sometimes wonder if it makes more sense to get a luxmeter and use a conversion factor to estimate pars, based on the cost of the quantum’s.  

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If you're doing it as a hobby then you don't really need the quantum sensor, but if you need accurate results for a potential product then its invaluable. 

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  On 5/13/2019 at 8:45 AM, greenkush said:

Cool, yeah i'm busy designing my own lightning system, hence my reason I got one. I also built my own color spectrometer that allows me to check the wavelengths. It seems relatively accurate if I compare it to a friends 25k one. 

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Nice one with the spectro. I want to go that route too! PARs don’t tell the whole story without knowing those wavelength breakdowns. I’m gonna work on that this week. 

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  On 5/13/2019 at 10:05 AM, iGrow said:

Nice one with the spectro. I want to go that route too! PARs don’t tell the whole story without knowing those wavelength breakdowns. I’m gonna work on that this week. 

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Thanks, it's pretty ghetto at the moment and my aim is to write a very watered down version of the software to get it on a PI or some other controller. I would have liked to have gone the Atmel route but its just not powerful enough to interpret the data stream fast enough and do all the colour calculations.

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  On 5/13/2019 at 6:18 PM, iGrow said:

Advanced stuff. Really interested in how that turns out and any testing you do. I wanted to setup my Raspberry onto something like that eventually, doing pH now. Still figuring it out. 

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I've designed an automated PH up/down mixing solution. PH probe that runs to a controller, controller controls a impellar to mix solution, another signal controls a peristaltic pump and then its just a matter of doing some base line determination in order to figure out what the total  PH increase will be based on the release of the pump, once you've done that you write an formula to determine the run cycle of the pump in order to achieve the PH level. Obviously some caveats would be impurities of your water at that point in time. In reality for small scale use its kinda impractical, but when you're dealing with huge grow ops it would be far more beneficial.

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  On 5/14/2019 at 8:23 AM, greenkush said:

I've designed an automated PH up/down mixing solution. PH probe that runs to a controller, controller controls a impellar to mix solution, another signal controls a peristaltic pump and then its just a matter of doing some base line determination in order to figure out what the total  PH increase will be based on the release of the pump, once you've done that you write an formula to determine the run cycle of the pump in order to achieve the PH level. Obviously some caveats would be impurities of your water at that point in time. In reality for small scale use its kinda impractical, but when you're dealing with huge grow ops it would be far more beneficial.

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Ahhh. I did a lot PDI controller coding at varsity... will need to do some serious catch up and refreshers in PLC to get your type of setup going.

Controlling the pump to address pH... there must be some serious dead time/lack of proportionality issues with that... or did you get around that by pre-mixing an acidic buffer and pumping as the pH goes up? I’m a bit confused how the impeller needs to be controlled to affect pH? Sounds like a really fun DIY project! 

Edited by iGrow
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