The cuttings' pellets got misted once with 1 drop of superthrive and one drop pf 6-4-4 in a quart of water for a bit and the dome was misted with that same mix for a week or so then I switched to straight water.
The flowering plants get one drop per gallon of ST and only once did I get up to a 1/2 strength nutrient mix from the normal dose of 1/4. I've only mixed Grow Big and Morbloom once, after the flush, and they were both at 1/8 strength. They've only gotten molasses once, 1Tbsp/gal and that is just before I noticed the "burn" the worst.

The cuttings exhibit an entirely different set of symptoms. Number one, not rooting. Two, sporadic yellowing. Three, leaf tips curling up into tight little horns.

I only notice "burn" or "spots" on the fan leaves, too. The growth underneath is lush and green....

I test the pH regularly by watering one plant a little extra, 100ml or so, catching the runoff and measuring it with a pH test kit for aquariums, three drops and blue-blue green.

Here's another, almost related question:

A 20-20-20 nutrient solution at 1/4 strength would be a 5-5-5 solution, right?
Is there any need to dilute a 6-4-4 then?!