Hey GC So after proudly remarking to a friend last night how well my first grow was going, I guess sods law decided to intervene! Turned lights on this morning only to find that the 4 taller ladies are experiencing major curling issues at the upper leaf tips....mainly curling up, but a few down, giving the eagle claw effect.... Naturally I have looked for possible solutions before posting this, but it seems that people suggest it could be anything from heat stress, nute lockout, ph issues, additional calcium required...etc etc. Hoping somebody can maybe narrow it down slightly? The girls are in coco, under 600w HPS cool tubes, temps are around 26-28 deg lights on, down to around 18-20 deg lights off.....I have a 12" oscillating fan blowing over the canopy, and ph feeds down to 5.6-5.8. Tried to show the worst affected in the attached pic, but quality is shit with lights on....apologies. Any advice is appreciated as always!