Led advise needed. How many umol at canopy and photobleaching causes

[Ralf]

@EGI_A-Aron

I just look at a max ppfd of 1200 to 1500 with co2.

I think a light with IR and UV, not only controlled separately from the main light, but also separately from each other, is the way to go. Are they necessary for good yields and great flower, no. But used properly, they can sure help.

I agree a max PPFD of 1200 is a good target for most growers. At that PPFD, 1000-1200 ppm CO2 is ideal. I also agree ~1500 ppm is the max CO2 anyone should use (specifically, 1600 ppm), but only with very high PPFD, and there’s never a reason to exceed 1600 ppm CO2. People forget elevated CO2 brings adverse effects, including reduced transpiration and uptake of mass flow nutrients caused by reduced stomatal conductance.

But, FWIW, science disagrees with you regarding UV and cannabis. Far-red (701-760 nm) does has significant photobiological effects. Still, we only want a limited amount (<5% to total PPFD), and we don’t want any IR beyond 760 nm. For an in-depth discussion on far-red, check out my comments in this thread:

DE Metal Halide Lamp

My build is finally starting to come together and since my nursery will only be completed in the fall I’m going to use one of the flower rooms for a nursery/ veg room for a few months. I’m using luxx de fixtures in both flower rooms and want to install 1000w de metal halides in the nursery room, I was wondering if anyone had recommendations on good lamps?