Not This Shit Already

Not sure what this is.. Trying to get it early before it becomes a big problem, please give any input.

System : DWC
Strain : Northern Lights
PH : 5.7
Water Temp (Now) 75ish (last night) 85-90 *BADD*

No visible root infections.

Hey man that shit sucks I had the same thing on my Sensi Star and couldnt get any help. but was able to stop it on my own so, first are you using RO water? if so are you adding Cal/Mag?
and are you foiler feeding/or misting with water at any point?