Is this ph or root problem? Maybe wind burn? Idk.

[Poundcake818]

Hey guys. Just trying to figure this one out. Doing a lot of research cannot find much. I currently feed my Kush mints At around 5. 7-5.8PH. I am in 8 inch big mama rockwool cubes. I’m currently using salts.

I’ve been doing this for several years and I have never seen this before. This is the first time I’ve used big cubes. Now I’m wondering if there’s something inside of it causing the plant to react this way. Is there anything I can do to change this? I’m only in week one.

Here are some pictures below!

Ty
Poundcake

 

[Mr Bee]

Looks like could be wind burn.are they close to a fan? Or too close to a light?
Some cooky Dom phenoes don't like a lot of direct light.