Trainwreck from clone new growth curl

Trainwreck 30 days from clone. Was under 200w t5 now under 600w hps. Grown in ffof. First three weeks no nutes fed 2ml GH grow a week ago. 2day under hps and new growth is curling under. No sign of burn. Pot was light so I watered so I thought it was bc it was under watered. First night under hps got a bit cold maybe mid 60s day 58 ish night. Stable temp now 75f 40%rh and gave them a gal and a half each @6.3ph this picture is 24 hrs after watering. Any ideas what could be causing this. Is it the switch from t5-hps. Air cooled hood is 12-16inches away all three pLants same symptoms. Any help would be greatly appreciated

They are in 5 gal pots also and leaves feel normal to the touch.

Heres something you could try. From the pictures you should try no feed for a week. The dark colour is a sign that its got its needs coverd. (maybe when you start feeding again, cut the feed with 25%). You have a big pot compared to plant size, letting it dry more out would help. It should perk up within a week with healthy grow. Letting them dry out will also cause them to grow faster and make more use of the neutriants you have feed them..

I wouldnt change anything else, they are looking good, exept for the droopyness. Almost as good as my purple trainwreck

Thanks for the input guys. My girls have perked up and look great again. Only thing I changed was raising the humidity up to 50% and temp up to 75-78f. Going to go with water water feed from now on. Anyone have a recommendation on how much to feed with the three part GH flora series?