I’m having trouble understanding ppfd. Not the concept itself but just understanding how far I need to have my light and which intensity. I attached a photo of my led lights chart( it’s a mars hydro 800 watt). Can anyone help me on the distance I should have my light from the top of my canopy? I am in 8 week of veg .
I’d stay about 24" - 36" and turned down to 40%-50% … just my opinion but it’s a starting point 
… you’ll have to watch her reaction to the light… turned down leaves, burnt tips, stalk all bent crazy = to much intensity which can be solved by raising the lights or dimming more.
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Maybe this review by Coco for Cannabis will help.
Mars Hydro FC-8000 PAR and ePAR Tests and Review
I like this chart from LumiGrow
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Search this video on youtube. Id link it but Im casting the news to my TV. It will give you the hanging heights and intensity for all MH lights.
With the driver mounted outside the tent I hang my fc3000 at 19-21 inches
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This was very helpful @Docnraq. I felt like was taking a physics class trying to make those conversions. The light is hanging at about 35” from top of canopy and turned up to 50%, girls are very happy . It seemed like they weren’t growing fast enough so this could have been why.
You called it @anon1893985 , great instincts bud!
For sure! Ill link to a thread I think everyone growing weed should read. Understanding DLI will help you get the most outta your light.
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And please give the thread a like if you learned something
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One of the best threads here in the forum.
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I’m honoured that such a good grower and knowledgeable person as yourself would speak so highly.
I have to say DIY LED’s from Drb is an amazing thread to knowledge that is hard to find anywhere else even with the help of google.
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I checked likes on the thread. Rooting for you to get past 100. It’s getting pretty close.
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1 closer @MidwestGuy .
Hey Matty… everyone 
glad it worked out for you… I’m new to growing indoors also but i read, watch, listen with 100% attention so i can avoid rookie mistakes… don’t forget bro that there’s people on this site that actually cares about you and your grow… you’re never alone on here so feel free to ask no matter how dumb you think it is… 
Thx 
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100% @Docnraq , I am so grateful for this forum and all the people on it such as yourself. This forum has saved me so much time and headaches figuring things out on my own and having a community that definitely seems to care is invaluable so thank you to you and everyone else for your continued support. I look forward to continue growing as a grower ( haha ) and look forward to sharing my experience along the way. Thanks everyone!
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Very nice bro. hit us up with a pic when you can… 