Tips curling down. See pics and help please!

so i got a blue mystic auto flower growin right now. the tips are curling down though 089.jpg. the ph is about 5.5 6.0. im growing with a trinity deluxe 2.0. the top feeders are on 4 times a day should they be on more?? there under 18/6 light 400 wt hps. here is another pic, 088.jpg087.jpg please help!
 
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