Photos. Experienced help please. Plant leaves conoeing and sagging

Hello everyone. My plants are 30 days into vegging right now, 16" tall, looking very healthy usually. Growing in rockwool grow medium, 600 watt MH lighting, AC room never over 80 (usually 77 but it has been very hot lately) in the day, and down to 68 night. I can't figure out whats going on with them.

I'm sure I didn't over nute them but when they did this the other day I flushed them for 2 days and they looked much better. Today I gave them a low 600ppm nutrient solution and already this evening they are canoeing again and sagging??? For nutes I am using VITA GROW (micro nutes), VEG, AND BLOOM (no bloom yet) three part fertilizers. I always make sure my PH is 5.5 although I am thinking I should check the runoff and see what its coming out at. My other thought was possibly too close to the lights. They are well ventilated so no heat is coming down on the plants but they have grown to within 9 inches or so. Any help would be much appreciated. I haven't been able to find any photos of anyone having a similar problem before. Thank you.

I've posted photos of two. Three of the first and three of the second. Hopefully someone with more experience can help.

Put your Temp. meter at the canopy then check your temps.Your light might be too close

Thanks jcdws. Thats what i was just thinking after looking at the photos again. It seems like the tops have the affected leaves more than anything. They just went to sleep so when the lights come back on i'll raise them up about 18" away and see if that helps. So you agree it's probably not a nute problem?

i agree with above poster, 9 in is close and at that distance the uv/radiant heat could be vaporizing some of the moisture from the leaf causing it to be stiff in spots and not in others causing the wrinkled look, i too get similar results when lights are to close but mine curl right on the edges...though i feal its a fine ish line to walk because a plant with slightly v'ed leaves is a good thing showing good cell wall structure and strength of the leaf system and accompanying roots.
if color looks good and no edge curling occurs then just back the light away 4-5 inches and see...also the flushing is like and overwatering and that too can cause droopiness...but my money is on the light distance

Yeah it's not a nute prob,leaves cup upwards in attempt to cool themselves down,glad to help good luck

Thanks MaintMan. I didn't really feel heat with my hand over the plants but didn't think much about uv or radiant light/heat. I hear what you're saying about flushing and overwatering but growing in rockwool grow cubes it is near impossible to over water. It pretty much just runs right through and the rockwool holds just enough. I have to water twice a day, most of the water I pour runs out the bottom almost instantly, and that is only two gallons per plant sitting in 25 gallon containers. Jcdws I will take your advice and make sure my temp meter is at canopy level. Right now the meter is high, being that heat rises, but having it near and at canopy level is probably better. Thanks again both of you.