I wouldn’t worry (as much) about mold with humidity around 20%, not unless it’s closer to 45-50% really. You would notice some leaves visibly “sweating” here and there before the mold strikes. Usually it’s leaves that are touching one another where the sweating occurs, but sometimes the buds themselves will sweat and you’ll see droplets on the leaves that are connected to the buds. If you don’t see drops of water on the plant that’s even more reason not to worry.
The red stuff might just be genetics as the plant doesn’t seem to be close enough to the light to be caused by bleaching (where the leaf loses its chlorophyll and goes white). Have you had some extra-cool nights lately or anything? Sometimes wild temperature swings (to a lower temp at night) will bring out purple/red/black leaves in some strains.
! Just to confirm, as soon as the lights are off, you lightly spray her with the mixed solution and then leave the Grobo door open to allow it to air dry before closing the door?
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