Purple Kush Wilting during dark (night) cycle

After reviewing many other posts here about wilting... I'm thinking this is normal. But would like to hear some opinions from experienced growers here.
I have been growing successfully with other strains for the past couple of years with great results !....... Until.... Purple Kush. These things seem to be the most sensitive strain I've come across. Especially root health and nutrient mixes. Anyways. Here are the specs.
Purple Kush.(clones). Vegged 3 weeks till 20" tall. Transplanted to Flowering area a week ago. So in 1st week flower.
Hydro...DWC and Eb & flow cross. ( 4x8ft trays) Plants supported in net pots with lid. NO medium in trays. Flood and drain trays every 15 minutes.
144 plans total. 4 4x8ft trays
800PPM. Ph 5.8 to 6.1 Nutrient temp 67F. GH 3 part mix. 6ml grow, 10ml bloom, 8ml micro. Per gallon
Using 8 airstones in 60gal tank and Hydrogen Peroxide 4ml /gal.
Room temp 78 to 80 F . Not using Co2 yet. ( start in week 2)
Multiple air circulation fans
8 1000W HPS Light pipe cooled. ( on light bar rack )
Plants growing 1 to 1.5 inches /day.
Thermal image(temp) of plant tops not exceed 84F.
Night temp drop less than 8F.
Humidity 50 to 55 constant.
Missed anything ??

Whats happening.... Light off at 8AM. Plants very healthy even leaves are pointing at lights. By 9AM minor wilting showing on tops. by 10AM wilting heavier and covers top quarter of the plant. But by 2PM or so they are all back to normal. Lights on 8PM And their perfect ! Growing well and very healthy the entire day cycle. Then Lights off and the wilting begins again... See pics.



Hope I didn't boar anyone reading this. Just wanted to give full details.
Hope someone can help put my mind at ease.. Regards.

iv seen plants do that outdoors, ive never been sure what causes it. iv never noticed it indoors but its not often that i look at my plants while the light are off. if you dont see any other problems it shouldn't be an issue. maybe someone else knows whats going on. your plants look healthy in the shots with the lights on

Thanks for the input SCCA. Yes they are very healthy overall. Just hate to see wilting at any time. They look lime green in the pic. Thats cause of the HPS lights. Just checked on them now and there perky again.. lol

my hypothesis on this is that as the air cools when the lights go out the plants lose the ability to transpire at the same rate and they wilt because they cant take up water as fast. im probably totally wrong but whatever.

strange. I have never seen this before. My question is this. Do you think that this wilting effect would affect whether or not they are taking in the right gases from the air at night?

it happened to me once.i never worried about it.i just believed they were having a kip,and then when the lights came on they woke up.

if their growth is normal and healthy,things should be fine.

STOP LOOKING AT YOUR PLANTS WHEN THEY ARE SLEEPING!!!!,when lights are out leave your plants alone,you've no need to check them at lights out,if you keep going in there and disturbing them they will start growing balls!!!! then all your hard word will be wasted

Hmmmm... O2 vs Co2 levels ?? I should note. There is cycle time, heat and humidity controlled exhaust fans. Air in room exchanged at 1200 cfm average.
Good idea thou. Wonder too if there is something else along those lines.

Oh ya... Wilting during the dark period.
I found out it was because of lack of O2 levels in nutrient ! When I added alot more air stones and big air pump. The problem went away immediately !

I too have same issue,problem with my plants wilting heavily during dark period also,i was very concerned thinking they were dying on me,but by the time the light cycle goes back on there up & looking fine again, wish i could answer your question,but i'm looking for an answer myself,i've googled & read countless forums & still cant quite find out why,if you find out the reason why or anyone for that matter please inform me,happy toking,peace...