Cupping Leaves - Help please

[Bender8982]

The first pic shows its best, but i included the second. i don know what my problem is here, im guessing its over-fertilizing? if so, do i jus flush my res, and go light with the nutes for a few days. if not, any ideas what it might be? also, im growing in a recirculating DWC. thank you so much.

 

[Icemud]

cupping a lot of times means either too high of heat, or too low of humidity..

 

[Bender8982]

Thank you. My heat stays between 67-77, so i dont think thats it. but my humidity can drop to the 40's or 50's, maybe i need a humidifier.

 

[WizHigh]

its not over fert, its low humidity and it looks as if it may be about to go threw some salt build u. Leaves look dry. Run clean fresh water over the clay rock

 

[Bender8982]

thank you