Bud leaves closing

In both of my rooms I have
chocolope
magnum
Alaskan skunk
white widow
all of them look great except the magnum on that strain only in both rooms the bud leaves have wrapped and hardened around the buds or the bud sites

here is what i have done

1st of i bought and used ph down i used 5 drops to 5 gal of water
that i was told may have been a heavy of a ph fluctuation
so i used foxfarms sledge hammer to flush 1 of them on another i used straight water and on 1 more i used 1/4 tsp per gal of superthrive
to try to fix so on my weekly nute day {foxfarms line of 6}{ works great.}
ok 3 days later the magnum still have not changed please help this one is tough

Im confused.