Clones....agggg....I'm clone clueless i'm afraid. You can go with a ph meter or in a pinch you can use a liquid ph tester from a pet store or hydro store.....the liquids are very cheap and will work fine for a soil user.

My first thought on looking at your MANY photos was a ph issue. The water you use should be a ph of 6.2-6.8 and so should your soil runoff (after you water what drains out...check ph). The thing with clones is that I've read that sometimes they do turn yellow during the transition phase so can't really say about your kids whether its a problem or normal. Where the heck is Stinky when you need her? Fox Farms is good soil and you say your other conditions are good. Hopefully a clone soul will pop in and offer some info.

Ideal humidity is in the 30's imo....don't go above 45%. I DON'T think humidity is your problems here however.

Sorry I'm not more help.