The thing is 7 is borderline bad PH, so some plants can stay right on the border and be fine, while others just barely cross the line and look like yours. Dunno if that makes sense, if not smoke a few and it might, I'm kinda high, ha. I'll be best for all your plants though if you get them down to 6.5. They might not looks sick, but your yeild just wont be what it could be, ya know?Anyways, to lower ph you need an acid, (alkalines raise ph acid lowers) and a great organic way to lower ph is lemon juice or something else citrusy.