With info offered, I call 'em like I see 'em. :thumbsup:
Likely the curling leaves with burned edges that looked like ph stress and/or overnute is actually a result of the anti-mite stuff. Some are harsher than others, and all of 'em I'd rinse off with ph'd water, and raise lights till dry. From what I understand, it can clog the pores restricting transpiration and aspiration, and on a plant already stressed by mites, a little tlc is in order.

How does the new growth look? If from the spray, the newest growth shouldn't look like that. Old growth with the worse signs will likely die-off. But plucking them off may add the final stressor before nanners, so use your best judgement and an abundance of caution.

Do you fish the clay balls out after every grow? (curious)

6.5 ph is ideal for peat based mixes.