leaf problem with pics

any one know whats going on with my leafs?
forth cab grow,
soil with perlite+vercumite,
400w mh,
temp 30c/day around 5-10c at night.
humidity 35%
run off tested ph of 7 (might be a bit high i think)
good ventalition
i only water when light and dry about every 3-4 days
gave them there first feed yesterday half strenght bio buzzz grow
4 weeks into veg,
3 power kush and 2 super skunk.

seems to be the 3 PK with the symtoms. the SS seem ok
were under flouresents till 4 days ago with the same problem.

other than that all is well

thanks for havin a look

Pretty warm. My first impression was low humidity for the temp. Is she real thirsty?

in about 3 days there dry and take a fair drop of water till some comes out the bottom.

See how the leaf tips are also pointing up? That why I suspected a moisture/temp issue. Try watering a little more on one of them. Since the others are ok , can't be anything way out of whack. Maybe this strain needs more water. Otherwise they look great! But man , need more opinions.

bump coz there getting worse
got the humidity up to 60 hope it will help