HELP! GSC "Auto" yellowing old leaves 😢

[Kristie25]

Hi y'all,

These gsc "autos" (only flowering now at 15+ weeks after I switched lights to 12/12 :/) are suffering seemingly the same thing (both get the same treatment). They're kept at 24C with plenty of air circulation and have 2x 75W CFL's and a 100W LED board. Water them whenever they're dry about an inch down usually 3ish days feeding with Canna Terra flores on their schedule and potted in Canna Terra pro medium. I use a dropper kit to test pH and seems to be on the mark out of the tap once I add the flores, about 6.3.

They have been a problem since the start and it's been so long I just don't want them to die now they're so close 🥺. The yellow leaves are advancing up the plant quickly starting with the oldest leaves. Leaves go yellow/chlorotic before the veins while they remain green then eventually dark/purple and the serrated edges seem to also curl upwards and go purple?

Help 😢

[Rwise]

My first comment is these are not autos! The auto strain finishes in 9 weeks per the breeders (ok add 3 more for amber making it 12 weeks).
The way I read you is these girls have been on 12/12s for 15+ weeks, you need more light, that 75W CFL is likely only about 15-20 watts or so, and the LED is likely less. My 2000 watt rated LED pulls just over 300 watts from the wall.
In the 4th pic I see curling, look for bugs with a 30x zoom lens.
I think they are hungry.

[MeEasy]

I think your plant is very hungry for light and nitrogen possibly potassium as well. Spider farmer has a really good deal on their old version of the sf1000 it is the same one they have now except the old ones don't have a dimmer imo a dimmer isn't necessary on a 100w light anyway but they are 60 bucks cheaper than the old ones @ $100 US. As for the deficiency of food it's either a ph issue (lockout) or it just needs a lite dose of nutes because it's eating the older leaves in desperation to develop the buds and why it's taking so long to mature. Hope this helps you out.... good luck

https://www.amazon.com/Spider-Farmer-Compatible-Samsung-Spectrum/dp/B084L1Y7KR/ref=pd_all_pref_5/130-2540860-0572148?_encoding=UTF8&pd_rd_i=B084L1Y7KR&pd_rd_r=5fbf44cd-b505-47a7-9a63-a3134ab088e1&pd_rd_w=w5RfU&pd_rd_wg=icGMv&pf_rd_p=e6474b7e-8fb6-4ee2-b5d6-a1da55185fe6&pf_rd_r=019M6QMXEEJCMJF5W75E&psc=1&refRID=019M6QMXEEJCMJF5W75E

https://www.growweedeasy.com/cannabis-symptoms-pictures