I’d say 18-24” from canopy
Mfg should have a recommendation based on par value
As far as the summer situation, I’ve seen no real value, it’s cool and all but makes no diff
I’d start at full and keep it at full for thr duration of veg/ flower respectively.
I can see the dimmer used in a manner when the plants are small/ seedlings, dial back the par value and not fry the lil ones .
Other value if the system has that capacity, is to dial back the blue light value during flower to prevent the stretch. Blue light causes stretching and Larf bud development.

You will need a PAR meter, or a lux meter to make adjustments with confidence and consistency.
My tallest plants have finished their stretch, and are about 18” from my led, which can go no higher in my room. So to avoid burning my top buds and still give the lower ones adequate light, I use a lux meter readout x .15 to adjust the dimness so the top of the canopy is no higher than about 900 par. At full power my lamp hits 1200 par at 18”, so it is theoretically bright enough to light burn even though the temps are well below 85 degrees at the canopy top. As my picking date nears, I have cut the light back in very small increments to mimic the fall sun.
Using a meter also allows you to “see” where your lamp is stronger, and weaker, so you can adjust plants to “the sweet spot”.

Kidcubby said:

Hello everyone,

So I like many others have started to switch to spydr 2I LEDs for both veg and flower. There is one thing I'm hoping yall can clear up for me and that is I bought a controller for the light that can dim the light from 1% to 100%. The thing I dont understand is how to apply this, I do know that it's nice for imitation of the sun rising and setting, but should I be using more of a dim for veg and full power during flower. And if so how close should the lights be during veg since it's less power. Or does non of it really matter and I should just keep them at full power.

Thxs for any help

Click to expand...

Fluency recommends the light be 6" to 12" from the plant