Mate, that's an old thread. Don't be surprised when you get no answer.. at least not from him. Have not seen him since a good while.
The Timber 600w produce a hell lot of light. 60cm/24" should work but it depends also on your grow area.
Is it a tent or open space?
A 4' x 4' or 5' x 5'?
It is not the distance what cause bleaching, it's the intensity.
If you can get a cheap lux-meter from e3ay or am4zon, get one(12-15$, smartphone apps are no accurate enough).
50.000lx are around 750-800μMol/s and that's a good range to keep your plants happy.
But it depends also on grower skills.
With higher intensities it get's more difficult to keep the plants healthy. To keep 85°F/30°C with ~60% humidity is more difficult the higher the intensity goes. Above 800-1000μMol/s PPFD you also need additional CO² so the plants can realy profit from higher light intensity.
For that reasons I recommend always a target intensity of 700-800μMol/s/m². The Timber 600w can probably hit this numbers over a 5x5' or 5x 4' area but need's at least 20-24" to get nice and even measurings across your area.[/QUO
Thanks man I just saw this was that old of a thread. I’m growing in a 4x8 tent with the timber on one half and a different lift on the other. I’m growing 8 plants all together with four on each half of the tent. RH is set at 60
And so far I’ve been able to keep the temps in the mid 70’s light on and high 60’s lights out. I was keeping the lights at around 12 inches from the canopy with no ill affects but figured I better raise them and I wanted to cover more of the outside edge of my plants, so it’s up higher now at 20 inches actually. I’m growing in soil and not supplementing with CO2. I’m ordering a PPFD meter today so I know where I’m at. Honestly I’ve never used the dimmer one time, and never understood why in the world I’d want to dim the lights unless my plants were growing too tall and had to so they wouldn’t burn. If I can turn them down and still get at least 600-700 PPFD then that would be amazing . I’ll let you know and I appreciate you input. Here’s what they look like last night, day 34 of flower.