Help!!!!

A plant will not drop leaves if a cold front is approaching. Something in your grow space/system has caused this, leaves like those in the picture don't fall off for no reason. But without a diary or much more information, like NorCalKannabliss said, answers would only be guesses. I very much doubt this has occurred just because the light has been upgraded. Thank you.

I need a diary not just pictures of the leaves to tell you what's going on. 🤘😤

the 12 hour example -- all relative. If over 18hours yo need 33% less than the 850 i mentioned. A DLI chart can verify this by using the value at 18hours, 850 ppfd. which is probably 35-40 DLI. Anywhere that value is the product, it's the same amount of light provided per day (whether 12 hours or 18 hours... .all proportional)

new lights take adjustment. need to know more to be certain.. BUT, if you are providing more light, you will have to feed more too. There is an upper limit relative to your ambient environment and time. If you don't add co2, about 850PPFD is the ceiling (over 12 hours). That's umol/s per meter squared. That's not considering temp and RH%, which will factor in too. I mention this to look out for light burn. Those leaves just look like they've been cannibalized. Try to maintain the ratio of nute you used before if they worked well, but up concentration 10% and see what happens. As a guide, you want your N to be around 120-130ppm. Without all the info needed, best guess is these just need to be fed more with a much better and more intense light than you had before. symptoms of light burn -- top leaves will look wilted and curl to reduce surface area / reduce photosynthesis.small spots will form, but expand out quickly on leaves. If buds have formed, the top will show a small lime-green spot with no hairs growing out of it.. that spot will expand too. If it is extra droopy for last X hours of lights on.. probably too much light for the 24hour cycle. i have similar setup - 12 bars and 2 240w drivers (2 fixtures, not one). about 1200 diodes. If significantly less than this, they are being driven a bit too hard and won't be near a 2.8umol/s or higher efficacy that is often advertised with these diodes. If you got about ~35-40w per 100 diodes, it's a great light and keep adjusting to how the plant behaves. if it's driven a little hot, it can still be an awesome light but will generate a bit more heat. if you are 220v vs 120v this may impact some of what i say a bit. i'm not an electrician, but V x A = watts. 220v in these contexts is more efficient, if not mistaken.