Brown spots to fan leaves dwc help please

hello guys i run 5 gallon dwc
600 w hps veg flower
ph 5.6-5.9
ec 0,7
advanced nutrients ph perfect 3 part + tarantula voodoo juice

the plant before 2 days it was very healthy , yesterday morning detect small sivler sport and about after 8 hours later turn golden brown very fast this happent only to big fan leaves upper

the roots are white and very healthy

wtf happened?

i search to internet it looks like calcium or phosphorus deficiency

any know what is this ??

Silver spot

Silver spot

Maybe thrips . but dont look like it from your pick.

Ph seems low but i am a organic soilless guy . i figured sence ypu have not got a response i would at least try . hopfully some one that runs dwc can step in and help .