Help Diagnose Please

Plant number one has some discoloring and very small brown spots.
Plant two has very skinny leaves with slightly yellow new leaves.

Soil: Happy Frog & Perlite (50/50)
Light: 240w QB LED
Temp & RH: 78°F-85°F 50%RH(Slowly dropping for flower)
About day 41 from sprout, 10 days in to 12/12 Light schedule.
Fed once at about 1/2 strength using GH Flora series and CalMag PH’d to 6.5.

Only thing I can think of is a ph issue due to my runoff being slightly acidic(5.6-6.0)

Any ideas or remedies?

Bump

Runoff won't be very accurate realistically, better to take a soil sample.

With that said, you're probably right that it's ph lockout.

Plain water, 6.5 - 7.5, water until runoff. Resume fertilizing the next watering. Maybe you are feeding just little too heavy?

If the yellowing keeps up, i'd give it a little Epsom salt.

GL