The leaves drying out I,m not too familiar with but have seen this question many times , the usal responses are low humidity , fans blowing too much on the plants and such. There are many ways to add heat to a cab grow . Whats the specs on your grow areas ? Is energy cost a big concern for heat . I run my veg 24/0 to provide a constant temp up in my flower area .Split cab though .
That spotting in pic 3 ,and it's kinda haed to tell my immidiate thought was spider mites because they are small yellow spots.But it looks like the spots are near the fringes of the leave indicating mabey calcium def? Keep an eye on that to see what it does for a few days .
(Edit) I keep my humidity in flowering 30-40% to help ensure no mold or bud rot.[/QUOTE
Spider mites can be detected with a plain white piece of paper placed under the leaves...shake the plant a bit...some will fall off. they are very small so wipe your hand over the paper. if you see small blood streaks, then you know it's mites. a 10x loop will confirm this. look underneath where they hide.
curling cupping and irregularly formed leaves are def a cal deficit is easy to fix. buy a bottle of cal/mag which is easy to procure. brownish or yellowish small spots are most times a mag deficit. the answer to this is two tbsp epsom salts into one gallon of water. water every day if in soil. idk much about hydro solutions but their is a mag/cal bottle at any hydro store or on web. mag is a mobile element whereby the plant steals it from older leaves and puts into new leaves which is why only older leaves show spotting. peace.