COCO GROW - PROBLEMS WITH NEW/TOP GROWTH

[Spottieottie]

Hey 1st time poster...I'm growing in botanicare coco and perlite 50/50, half gallon pots, 600 ppm, temp 75 F, humidity is 65, vegging under 400w t5, water to 20%-30% runoff. My plants all are showing these issues and I'm trying to catch it before it gets worse. My runoff ppm is at 670 - 700, PH in is 5.8 and runoff comes out at
6.3. The new growth feels rough and appears to be slightly twisted...my 1st thought is that I'm either underfeeding or have a ph imbalance or both but I don't wanna just start upping nutes and start burning the roots up if that's not the issue. Any suggestions/or problem identification would be greatly appreciated.

Thanks in advance!!

 

[Spottieottie]

I have also noticed, plants look a lot better if I turn the lights off for 6 hours, then after a while under the lights, this is what they do...which was making me think underfeeding.

 

[BurnzYzBudZz]

I have also noticed, plants look a lot better if I turn the lights off for 6 hours, then after a while under the lights, this is what they do...which was making me think underfeeding.

I always run 18/6. I don’t mind the stretch because well, stretch=yield. Your plants look good.

 

[Spottieottie]

Thank you. I try to stay on top of it. I switched them from 24hrs to 18/6 and I also raised the lights a bit. See if that solves it.

 

[Spottieottie]

So i figured out the problem. Somehow the vent to allow fresh air in, on my air conditioner, got pushed closed...so basically the c02 levels were being depleted below 400 ppm about 10 hours into lights on ...realized the vent was closed and set up a ppm meter. It was dropping below 250 ppm!! They looked amazing right after lights came on, but as the day went on, they looked worse by the hour. Crazy how big of a difference a little tiny vent can make. I popped that bad boy back open and it's already back up to 500 ppm. Had me stumped for about a week. Easy fix...this time.