Please help asap

hey all how's it goin. So my clones are almost 3 weeks now an we're doing really great till I came home from work today. I'm using a dwc setup 400w Hps. Cyco nutrients. I changed my Rez water last night checked everything twice befor goin to bed ph good temp good everything good. Wake up this morning everything still good go to work and get home one of my babies looks like she got trampled. All wilted an don't have a clue why. For some reason my ph in the res got up to almost 7.5 temp was a lil warm but ok. All the other plants look good what did I do?
Here is the plant yesterday.

And here she is today.






And here are pic of the others in same Rez.

may just be the stress..but the ph is too high also,,

remove dead/yellow leaves and get ph lowered..


luck.

Because the ph is so high s/b 5.8, the plants are yellowing ,wilting and dying from the lack of food which is locked out. Get ph down in the res to bring it down. The collapse is due to lack of N and K.

I always flush first then diagnose. Ph won't do that to one plant in a res. leaving others ok. I'd guess it got a hit of poorly mixed nutes. I don't see that kind/quick of change in less than 24hrs not hungry poisoned.

I lowered the ph immediately when I got here. I forgot to mention I did take a couple leaves off last night dying yellowed ones from lower on plant could I have stressed her that much. Anyone thing she will bounce back

They almost always come back.

God I hope this was my best looking one up untill tonight >_<

i had simlier problem once , found out not big enough res .water got little to warm, which through off the ph used to ph the water 2-3 times a day it was a nite mare then on more reseach found i needed more water to stablies the temp which in returns keeps the ph in checked and had a fantastic grow the secound time around ,hope this helps

Is your airstone working? Looks drowned or nute burned on some leaves. I nute burned one of my plants. Some of the leaves fell off and had some burned edges. It started to look like it was gunna get better then one night i walked in and it was droopy like that. It died. I think that the roots died and that's what caused it.