Ok I have a ? I have been watching videos on light spectrum from Dr Bruce Brugbee 101 and he says that during the veg stage on cannabis plants like the blue spectrum which which occurs around 350 ffpd to 500 ppfd. Now my ? Is does it matter how I get that level like if I run my full spectrum led light at 100% I have to raise my light up real high and makes my temp stay at 78 and humidity at 55 now when I put my light at 50% I had to lower it to get the level of 450 ppfd and that keeps my temperature at 72 and humidity at 61. So as long as I am giving it the right amount of spectrum should it matter the % of my light I am running this is my first grow
2 Likes
I prefer to keep my light turned up as high as I can and keep it up high to control the ppfd. I have noticed that the plants don’t get so sensitive to the light when it’s time to start increasing intensity, seems like they get used to the brightness of the light and lowering it to increase the intensity doesn’t seem to bother them compared to using the dimmer
3 Likes
New to led here too, 1st grow under led about 5weeks into flower. What I was suggested and found to work best is light at 100% and adjust your distance to get wanted outcome 
1 Like
And that above me is 1 of the 2 peeps that schooled me on thatđź’Ş
2 Likes
Same here i do the same thing
1 Like
Ok I will turn it up to 100% and raise them up as high as I can and take a ppfd reading to see what I get and let you know the out come and see if you can give me some info
1 Like
Yeah that’s a big light and you will probably have to dim it a bit even 48" away like mine has to be until probably 2/3 through veg then the plants pretty much grow to the light. I don’t have to move my light very much at all
2 Likes
I also prefer using higher watts and a higher light placement and the higher temps that come with it.
Plants will grow faster and have better nutrient uptake at 78F than 72F.
3 Likes
Just a point of clarification. blue spectrum refers to its wavelength
PPFD I would bugger it up if I tried to explain it. So I will leave the explanation to Fluence
Photosynthetic Photon Flux Density (PPFD) is the measurement of PAR delivered to a specific area. It is
expressed as micromole-per-meter squared-per second (ÎĽmol/m2/s).
This is the only measurement that informs us of the amount of light being delivered to a crop which
enables photosynthesis.
1 Like
Ok put lights on 100% and raised them as high as I could with moving my ac infinity system outside which puts the light at 44" from the top of the plants. I took ppfd reading and got 603 I then took a lux reading and got 26250 is that to much light
1 Like
It depends on what stage your plants are in the strain and in a way the attitude of the plants. Here’s a pic that will get you started but I recommend doing some research on DLI since you have a meter dli is the amount of light a plant gets per day while every plant is a little different learning how dli works will give you a better starting set point for your light but there’s no magic number for all plants
That is one of the biggest benefits of having dimmers.
You can do it either way as you are correct, as long as they get the light needed, it doesn’t matter if it’s high and bright or close and dim. …
I start with mine at 25% up close and raise it and the % as the plants grow…
I have a Growers choice Roi-e720 (720w at 100%) and I actually rarely turn it up to 100%. Where it a big light in a small tent, 75% gives me all I need.
The more you can run any equipment “not” at 100%, it going to be cheaper on the electric bill and last longer because it isn’t running full blast all the time.
3 Likes
Under normal home-scale conditions, cannabis requires a PPFD of 200-400 mol/m2/s during seedling, 500-700 mol/m2/s during vegetation, and 700-1,000 mol/m2/s during flowering.
You’ll need these basic food photons to grow strong and vigorous cannabis. These facts were also unfamiliar to me. This information was provided by a friend who works at a marijuana dispensary. I was under the impression that the higher the PPFD, the higher the yields. Greater PPFD, on the other hand, does not always imply potency, as every plant has a saturation point beyond which the benefits of PPFD tend to fade. At certain phases of growth, too much light can induce light burn, nutritional burn, and water deprivation. This is where the additional CO2 comes in handy.
2 Likes
This info is correct.
It’s really about how well can you maintain a stable environment.
To use to uper side of the scales like 1000pphd fir example. Temp, RH, and nutrients needs to be on point…
Some do go over this by basically increasing everything across the board, temp goes up, nutrient ppm goes up, co2 goes up.
It can get very technical and complex…
But it’s not necessary for most to push it to get huge yeilds of fire weed!
1 Like