my 2nd grow ... skunk #1 and pure sativa

ok so here they are my babies.. 4 weeks in now and planning to start flowering next week. soil is fox farm ocean something. 6 cfl daylight bulbs. blah blah..
first two pictures are of sativa and the second two are of the skunk and the last pic is the only issue im having

let me know what ya think

ok here is the leaf that isnt looking so good

Hello

I have some skunk no.1 seeds how are they any good?

when should i flower?

I'd wait until they were at least a foot tall.

my grow chamber is only 40inches tall will that be enough room if they start fflowering