3rd Gen Clones Leave Curl.

[IrishGent]

I have this clone that I transplanted from the soil due to an insect infestation. The clone has successfully rooted and taken off. I run a 400watt COB LED setup, plenty of space and not light burn.
I use General Hydroponics nutrients, using a mild veg mix.
The problem started a week ago, the upper leaves are starting to curl inward on the edges, the plant otherwise seems very happy and healthy. I have checked the PH and it's right around 5.7. I do not change the solution in the bucket, I do drain off 1/2 gallon at a time and replace with fresh mix, I am curious as to if I should clean the bucket? There are many schools of thought on that method, I prefer not to have to remove, clean and replace my mixture if at all possible.

Thoughts, suggestions, and advice are welcome!

This is a lemon haze strain. Pic's included.

[Newf]

This curling looks like heat stress. When the leaves curl in like a taco shell that is usually what it is. What is the temp in your room and how far are the lights (and what type/wattage?)
see the GWE site page on heat stress. http://www.growweedeasy.com/heat-light-stress . I use Silica to reduce heat stress effects but the best method is to reduce temps or move lights a bit further away.

[Flockshot]

I agree

[IrishGent]

Thanks for the reply. The temp is between 69.5 and 72.9 never higher. Humidity is 47.1%. The light is a 400W COB Full Spectrum LED. The light is roughly 8 - 10 inches from the top of the plant. I place my hand there and feel no discomfort.
Funny thing is that I have 2 plants in soil right beside this one and they are not suffering from this problem. After reading the post you linked to, I will place a fan in here again, I removed it awhile ago to use elsewhere. I will see if this has any impact. Update: Okay, I found that my temp sensor was defective. it was 76 - 78 degrees F in here. way to warm. I installed a fan, moved the light higher, I cant open a window, its way to cold outside up here in Massachusetts.

Thanks for the replies! I appreciate it, sent me in the right direction.

[Canyon Grower]

IrishGent , 8-10 inches is too close for an LED. These lights can cause "burning" even when temperature and hand test suggest otherwise. Its more about light intensity than heat. Check your manufacturers recommendation. Most say to keep a distance of 18-30 inches. Just a suggestion.....
Slainte'

[D.A.A.S.69]

Yeah ,that's way to close for those cobs.