A bit of droop at the end of the day is normal but I have noticed that mine are more prone to evening droop when they are becoming rootbound, but I'm growing in soil. Coco can tolerate a lot more root-binding and those pots look like a decent size, so it's unlikely that's the problem. Maybe they need more water, coco is hard to over-water anyway.

Have a look on youtube at some of those time-lapse videos of growing, plants do often droop towards the end of the day and I don't think it means much more than they are "tired" from the day's hard work in the sun. Here is good demonstration of that: YouTube - Cannabis Time Lapse - Marijuana Grow #2
PlainJane Reviewed by PlainJane on . plants droop before lights go out hey guys and gals got a problem and cant seem to fix it im growing in coco using ionic im in veg my runoff ph is 6 when ifeed them its 6.5 they are about 2 to 2 and a half foot in size a little scrawny for my liking picks on my profile, anyway just before lights out say at 16 or so hours the fan leaves near and around the top seem to droop im letting them dry on top before refeeding so its not water logged down ther roots are white nd healthy and lots of them just cant get my head round it this Rating: 5