The growing medium is unbalanced

I know your running co2 to help with the heat but your environment is out of whack a little. Your VPD is close to 2.0 after 1.6 I find most plants don't uptake food and water as they should do. Increase RH to 60% and that will give VPD of about 1.4 and make sure your ph is in the 6.0 to 6.8 range. Let your soil dry out a little in between feeds. Check your ppfd on the canopy to make sure your not to intense with the light. Good luck.

I also see your temp is 90f? And Humidity is 50%. If you cannot get the heat down, try getting the Humidity up to 75%. Also look up VPD charts. I have pictures on my diary of VPD charts for cannabis. Hope this helps

What I see is the petiole are abnormally dark redish pointing in P def.. But looking at your diary I guess this is a coco grow (since you're using Canna coco nutes). If this is a coco grow your problem is the ph being way too high. Especially for phosphorus absorption. Bring your pH down to 5.8 and see where they goes, but this should fix it. Or if this is a soil grow you are using the wrong nutes.. I know nutes are just minerals, and I, myself have used with success *to correct minor deficiency* Canna coco A+B in organic soil, but still there is a limit on using salt base nutrients in soil. Canna coco sure provide fast response, but it is designed to be run in a drain to waste setup. If you are feeding soil on a regular basis with it, I am pretty sure you are having pH issues. Hope this help

When I see this it’s because the root system cannot keep up with the plant growth, not saying your root system is bad, just can’t keep up. Try getting your RH% up and kick back the lights. This works for me when i see plants start to do this.