When to boost lumens during flowering?

Howdy RIU! As we head into the warmer months, I’m planning on scaling down my basement grow somewhat. I currently have two flower tents with a total of 3000 watts of HID and 950 watts LED (330w COB in one; 620w HLG Quantum in the other), plus an all-COB veg tent. Starting after chop next week, I’m turning the smaller flower tent (4x8ft) into a veg room and just running the larger flower tent (5x10ft), with four monsters in 25-gal grow bags, super soil (my state just legalized small numbers of plants for rec growers so I’m learning to max out yield from each plant).

I want to leave my two HID hoods and ducting set up in the larger flower tent (5x10) and put the HLG 600 quantum in there as well. This would obviously be way too much at full power for 50 sq ft, so I’m planning on running the HPS at 500w each (dimmable digital ballasts) with the Quantum LED at full blast, up high and in the middle. The quantum exceeds a 1000w se HPS in PAR output by about 20%, even before accounting for HID reflector/glass-induced losses. So I’m thinking these ~1620w in my 5x10 will produce more usable light than what’s currently in there (2000w HID + 330w cheap COB from Amazon).

HOWEVER, since I’ll have the option to dial up the HPS, I was wondering if there were particular weeks within the flowering cycle (running fast strains, ~8 wks in 12/12) where plants really benefit from turbocharged lumens. As long as I can keep it cool enough, I could pick a couple of weeks to turn the HPS up to 750w each. I use exhale CO2 bags which keep my PPM between 750 and 1250 in the tent, so I think they could use the extra lumens. Does anybody have experience with this kind of thing? My hunch would be to blast them in the second “trimester” of flowering, so maybe weeks 3-5 or so. But I could also see boosting their early development with tons of light in the first week or two and then dialing it back. Any thoughts? Thanks for reading; you guys always have some interesting pointers to share! Legal weed baby!!!! Happy spring!

I hate to simplify this so much but You already appear to be good at math.

Here are my thoughts
Give it as much as it can use, no more or less.

In my mind too little is silly when you have more, (unless like me in veg you use small lights because Im in no hurry)

If you use more than it can use
Why? It sounds like an invitation for problems like bleaching or heat and is wasted money.

Maybe a lighting expert will post something different and we can all learn so take that with a grain of salt

Side note, I have always wondered how dimming a bulb rated for 1000etc effects the spectrum.
Not enough to research it though clearly,

Ya, I do tend to over-complicate things. I was also thinking that the best strategy might be to crank them to 750w each on cooler nights (I run lights at night) and dial them back down to 500w during warm spells. It would be interesting to hear if any research has been done into when flowering plants benefit most from maximum light. Maybe someone can chime in with specifics.

As to your other point about spectrum differences when dimming digi ballasts, I have often pondered this problem as well. I did some research on it some time ago, and remember a fairly definitive post (most likely here on RIU but possibly reddit or icmag or something) convinced me that the spectrum is unaffected when reducing wattage, even when using the same bulb. I don’t remember if the post included spectrometer readings or just a reasoned math-based explanation as to why varying power draw doesn’t modulate spectral output, but I’ve been pretty satisfied with that answer ever since. If someone can convince me otherwise, I will definitely reconsider my setup. It would be easy enough to just take one HID down and run the other at 1000w next to the QB LED. I like the idea of the better coverage of three lamps closer to the canopy though,and it’s easier if I want to scale back up in the fall. Thanks for the reply

Your plants will never need the most of everything in any stage than the stretch. Within a week of switching to 12/12 their demands for food, light and extra CO2 if you have it will be at their peak.

Once stretch is over their needs drop back to veg levels prior to flowering but their nute formulas need tweaking to max them out. Lower N and P with higher K and S will see them busting up with phat colas sparkling with sugar.

A lot depends on lighting and temps to push them to the max. I use 1000W Super HPS on mine. I hurt those girls.

Wrong, the more lumens you give em during flower the better, just like when people use cfls for clones... then change to hps led or whatever as the plant demands more, whether it be food or light, increasing light intensity, specially in the last two weeks of flower does make a difference ( here's a scenario) you use a 1000w light all the way from veg to flower, eventually the plant will want more as it increases in size and that 1000w will do fuck all towards the end production compared to upping it to say 1400w+ you will have a better lightning footprint, better yield and possibly a better end product . So.....now you know something

there is a level from where your plant canopy will be saturated, you can push that a bit with CO2, but just to certain point and you would need to take more factors in to account.
the fuller your canopy gets the more the plant can take, simply due to the fact that the photons are shared over more leaves now.
so basically when you reached this point and your flowers are developing i aim to blast them.
this is often the case sometime during stretch.

there is some logic that the plants need the most during stretch, and i also saw charts proving this, but i also saw others...
my logic is just anectdotal, do as it works for you.
watch your plants and see that they transpire well, have a good posture.
if they do, they will grow well and fast.
watch for early signs of too much light, serated edges, unatural praying of the top leaves (or droppiness during veg).
otherwise see to max them out as good you can.
i would be camp week 2-6 for the blast.
before its more influencing how full your tent is, which is always too full in my case anyway, and need prunning.