The plants look pretty healthy overall and I've just got a couple questions/suggestions:
-Light penetration to low parts of plant may be insufficient. That would cause sloughing-off of leaves that don't get enough light to be useful to the plant.
-The origin of the coco- Are you certain that it was rinsed? Was it the good stuff, or one of the 'off' brands that carries a lot of residual salt with it? Even sunleaves is said to be a salty one. That's something to check.
-I see you are using a coco specific nute so I assume that it contains something to make up for the habit coco has of scavenging calcium.
The underside view isn't really something I'd be worried about. It looks normal- mostly healthy and green, a couple old yellow leaves, no margin or tip necrosis. Adding ventilation is a good call. If anything, I would suggest you are low on calcium but only slightly. In general those plants look pretty darn good. Consider a good flush before placing them into flower.
stinkyattic Reviewed by stinkyattic on . Leaf problem Hello, all smokers and tokers bit of a leaf problem indoor hydroponic coco medium dripper system tap water water ph 5.7 Rating: 5