You using CO2? What kind of intensity do you have the lights set at? From what I've learned is the higher the power the faster the plant feeds and feeds quickly to a point then if you want it to faster than that CO2 is needed. Also I've found with leds warmer temps are better, personally to get my plants praying I'm near 80 up to 82 degrees. Good luck!
I would,speaking for myself, cut that humidity down at least 10%.....looks like, I say it looks like rust fungus (That would make sense in moist environment)........ no expert here.My day temps are around 75 and now ggt temp's around 65 humidity is right around 60% I am in soil and run cyco nutes I ph right at about 5.8 because I get a swing my run off normally comes out around 6.3 my room is about 10x8 I have 2 growers choice 720w lights