Light output increase at flip- How Much, How Fast?

Here I am at Day56 VEG, about to switch to 12/12 to induce the flowering stage.

I'm in soil, 10gal pot, 2X2.5" tent using HLG 288v2 X 2 as my lights. Currently running at 125W to achieve 400 umoles at canopy level, the lamp is about 24" high. (I have a thread in the Grow Journal forum if you need more details.)

What lighting level am should I reach at this point, and how quickly should I increase it? Obviously I've got tons of headroom since it's dimmed to 125W. The 400 umoles is fairly even across the top of the canopy I assume my best bet is to increase wattage draw rather than lower the fixture.

Why up the wattage when you can just lower the light?

I’d turn it up like 25% and maybe lower it couple inches and keep an eye on temps and how the plants respond. Definitely wouldn’t get any closer than 18-20” away.

I check light lvls with a shitty phone app but it’s just for shits and giggles!
Anything you grow will tell you what it needs by its appearance and behaviour.

Renfro said:

Why up the wattage when you can just lower the light?

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Three reasons
1. I'm getting an even distribution of light as measured by my PAR meter. Although the tent is so small this is likely a moot point.
2. I'm already at 20" and that distance will decrease quickly with growth.
3. Mostly though I'm paranoid about stressing with the light. Already did that once when I switched to the HLG from a Mars.

pthobson said:

I’d turn it up like 25% and maybe lower it couple inches and keep an eye on temps and how the plants respond. Definitely wouldn’t get any closer than 18-20” away.

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So do you recommend increasing to 500 umoles at once, or smaller increments each day?

I would try to ramp the PPFD up to the 500-750 umole range, either with more output(wattage) or drop the fixture a few inches.