G13 needs help

Hello I have a G-13 plant under 12/12 of a 1000 Watt HID light. I have been feeding it with IONIC nutrients for soil with a ppm level of approx. 800 which I have recently increased to 1100 ppm. My feed solution consisted of super thrive at 1 drop per gallon. PH level at 6.0, and the feeding schedule has been two days on one day off. I have recently implemented CO2 to my grow room and the temp. has risen to 80-90 degrees and RH 57%

I am having cupping with my old leaves, tips of new growth are turning yellow. I am in the fourth week of flowering. These problems began before the increase of nutrients and the implementation of the CO2.

Thanks in advance for any help or suggestions.

looks to me like its some potassium, phosphorus, or nitrogen defeciency.

I'll say that is a potassium def. How is the stem ? is it weak ? reddish or purplish color ?

Looks like heat stress too though with the way the leaves are curling up like that. How close are they to the 1000? MH or HPS? Whats your temps?

It could be a Pottasium def. Or a Ph problem. Im going with high ph and lockout. maybe.

Thanks for the responses. The stem appears to be purple on top and green on the underside. The top of the plant is 22" away from the light, and the temp. is at 75-81 degrees now, but it did get as high as 91 degrees with CO2 before I moved my air conditioner in there. The PH is 6.4 and the lights are HPS. If this is a heat stress issue are there any remedies that can help return it to normal health, outside of lowering the temps. Thanks again for any suggestions.

I still think there is a big chance of potassium def. It also causes the burning of the leaves because of the evaporation. That could be caused because a high salinity which could come from the feeding. All I read about feeding said that plants should be feed once a week. Please correct me if I'm wrong. I read that you are feeding once every 3 days ?

Anyway if you have lowered the temp and that was the reason, the leaves should not get worse.

Not an expert so just writing my thoughts here

I checked the soil and you were correct I was low on potassium and phosphorus. I increased the nutrients, ventilation, and cooled the temps, and they are looking much better. Thanks again for your advise it helped.