jemro86
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During your entire flower period? I basically have 3 of those in my 4x4 tent and 1.5 In my 2x4. I currently have the lights drawing about 500 watts in the 4x4 at about 24-28” and the 2x4 275 watts at about the same height. I had them a bit higher (power) but started seeing light stress and some foxtailing.I run mine at about 80% power, at about 28 inches. I run two of these (older version) in a 4x4. https://horticulturelightinggroup.com/collections/kits/products/260w-qb-v2-rspec-led-kit
Thanks. I have that meter actually and also the hydro farm par meter (cheapest par meter on the market, not 100% perfect but good enough for me), so I figured it wouldn’t be any different, but wanted to ask all you pros over here :)You’re right in that lowering the lights and running them at a lower wattage is basically the same as raising them and running at a higher wattage. The difference is cover. How much area the lights cover. I use a light meter to dial in my lights. Here’s the meter.
View attachment 1041542
More power at greater distance gives less attenuation of the light as it penetrates lower in the canopy.You’re right in that lowering the lights and running them at a lower wattage is basically the same as raising them and running at a higher wattage. The difference is cover. How much area the lights cover.
So if I understand you correctly then, you’re saying that let’s say if the light is at 24” and is putting out 800 ppfd at let’s say 250 watts (making numbers up for the watts, just for examples), and at 12” the same 800 ppfd but at 125 watts, that the 24” at 250 would be better?More power at greater distance gives less attenuation of the light as it penetrates lower in the canopy.
Hey, I appreciate the time you took for the response. I watched the video, and around the 7+ minute mark (6:51 exact), his exact words were "plants do not care how much electricity in watts that a light uses, how efficient it is, or how much light it produces in total, only the ppfd of the area it is placed in". Which, I would think, would mean that a lower watt at lets say 24" would be the same as raising the watts and raising the light to 36". As long as the PPFD is the same where the plant is, then there isnt a difference?^ Yes, more watts = more light = more light penetration.
While it's great that you've understood the concept of PPFD, not everyone does, you have to remember that a PPFD measurement is a spot value. An increased electricity (watt) consumption means that your lamp is putting out more light in total (PPF).
PPFD = spot measurement of light intensity
PPF = total light output (imagine that you'd check PPFD on every single spot across your grow area, then add all the PPFD values together)
I recommend watching this video that explains the different terms, well invested 10 min:
How many watts your lamps should draw will come down to what phase your plant(s) is in. Since you mention 800 PPFD, I'm assuming that you're in mid/late flowering? In that case, you likely have a bushy plant which means you want maximum light penetration.
If you'd have a small plant in early veg, deep light penetration would not be as important as you only have 1 or 2 layers of leaves, i.e. not much to penetrate. Makes sense :)?
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