definatly hot soil nute burn?

is this for sure nute burn ? its from hot soil so i'm not sure if flushing is good.

temps 76-78 day 68-70 night
feed once few weeks ago with half dose roots buddah grow
spring water always in the 6'sPH with PH up by GH

I think so, hard to tell but looks like something I just had. I moved them outside into composted soil and added some Epsom salt and now all is good.

i did feed them some epsom slat a few weeks ago and some superthrive
i hope it stops spreading
i had to flip to 12/12 so maybe all the new growth will get them eating enough for roots soil