Sudden Droopiness/Limp stems... Help needed

Hello

I acquired a few sets of clones about 3 weeks ago...
they have been doing great and now all a sudden, a few clones have gone real limp and just drooping while a clone right next to them, is doing great.
I am using DWC/Bubblepoinics- I was thinking maybe its from lack of oxygen and not getting enough bubbles? So i am going to store now to get another airpump and air stones


Temp is at 75*
Humidity 40-50%
Res Temps are 72*

1st picture is a purple kush that has gone limp, 2nd picture is another purple kush that is still doing fine and right next to each other
3rd picture is a Northern Lights/WW that is gone limp and was doing awesome 1 day ago, 4th picture is same strain right next to the other and still doing great and sticking straight up

Very confused and annoyed, cant figure this out

You say it was sudden , you also state your res temps are 72 (which is a little high). The only time I've seen a sudden drooping/wilting is when we had a big temperature swing here and tap water temp dropped drastically and I did a res change without taking that into consideration, my plants wilted within moments. So you preheat your water to 72 f when you change it out?

Yes I monitor temps and always get it within 68-70* when i change the res. , I had a drastically cold res about a year ago when i was cleaning and noticed that dramatic drop and droop like you mentioned.
I havent changed the res. since last friday so there hasnt been a sudden change in that aspect. Have a heater in the room to keep it at 74*-75*
So perplexed right now, those plants are kind of on the outskirts of my lights footprint but this limpness has just come on all of a sudden so dont think low light would be the issue since its been doing great. New lights are coming tomorrow though, just worried it wont make it til then and come back healthy

What kind of water are you using?
I grew with tap water using the DWC and the plants growth was stunted, cant remember if it drooped or not, that was my first grow. but it might be something to think about. Im stupmed.
Whats the temp without the heater? Prolly dont need that.

Tap, Been using tap water for about 2 years now and no issues, have a huge chlorine filter for everything that comes into my house. Water ppm 180- 220 before adding anything to it.

Growth has been great lately, just these 2 bastard plants going limp on me.

Without heater, its about 64*. My basement is about 58* so hard to keep my area warm. Im using LED lights and they are just not putting out much heat so need to add something to keep them warm

Yeah, damn hows the led going?
And is the heater blowing on the plants? or close to it?

LEDs are kick ass, been perfect until this hiccup.
The fan is not pointed at then or hitting then, just like 3 feet away and warming the whole room

TTT

any help or input?

Did a res change and added straight water and hygrozyme (8ml per gallon)
pH of 6.4
68* F
210ppm before hygrozyme

the roots on these 2 plants feel too soft and peeled off when i touched them slightly, while others in the res were still strong and white

is this root rot or wtf is going on, and why are only 2 of the 8 plants affected, never had this happen and worried im about to lose my 2 best plants