Ppfd goals?

I am a newbie. I use both, but I have impression that by adjusting the distance I can see plant reaction faster.

ppfd without hours of operation is missing half the equation. DLI is the key, not ppfd. DLI is a tool.. not an exact answer. 35-40DLI is a good ballpark for ambient co2. that doesn't mean you can't give more or maybe need a bit less.. that depends on local variables. So, don't worry about others.. start in that ballpark, then adjust relative to how the plant grows/reacts. internodes too tight? needs less light. Internodes too lanky, needs more light.. simple as that. It will hasten this trial and error vs not using it to start... you'll have more conidence that what you are doing is up near "max" relative to your local variables. ------------------- Ambient atmospheric co2, temps and rh will impact how much photosynthesis a plant can handle per 24hours. If transpiration isn't optimal, it reduces how much photosynthesis takes palce. if carbon is lacking, a lower rate of photosynthesis is the result. On top of that limitation, you can't circumvent the the total of reactions related to photosynthesis... Outdoor plants mitigate much higher levels of light - beyond what it can use per day. Just because they can sit there under stronger light doesn't mean it is being used or beneficial to add more. It will adapt to 'too much light' in order to survive outdoors. you can cause this to happen indoors too. It will in one way or another attenuate the light received. maybe less dense chlorphyl/pigmentation? need a biologist for the exact mechanics. if you have 600ppm co2 and go above what a plant can do relative to that level of co2, then the plant is merely attenuating how much it absorbs or otherwise mitigating the excess.. adapting to too much light just as outdoor plants do. the molar ratio of the chemical reactions taking place cannot be circumvented.. laws of conservations of mass and laws of thermodynamics are relevant here. Even if it becomes robust to more light, sans additional co2 and proper temps to maximize rate of related chemical reactions in the plant, it absolutely is not using that light.. just wasting watts. Calvin Cycle... look it up.

If you have the Same PPFD at the top of the plant if the light is 15 inches away running 50 perfect or 24 inches away running 100%… it’s the same. The only difference is the cost to run the light. I do not like to get below 12” away from my plants with the lights. It’s really your preference on how you run, it’s not going to differ if your are indeed providing the same PPFD light to your plants. I hope this helps.

if they don't dim, height is best bet to alter PPFD but not everyone has that much head room to hang it high. I like to hang it to a point were as the the PPFD is even across the canopy, if you where to do readings then increase or decrease the intensity "dim" so its just more light thus giving you more PPF, I recently borrowed a quantum par light sensor from my grow shop. and found out my hang height and dim settings, I was nuking my plants before. I was giving them aorund 50-60 DLI vs 35-40 now. Its made a difference to know, So I feel dimming is a great tool and if you lack it you only have height to help diffuse that light. don't limit yourself and find the sweet spot then dim as needed. Good Luck!

Who wouldn't want a dimmer Taking into account full running cost the most