Ive just watched a mate ride an infestation of spidermite in similar circumstances,all he could do was spray the LEAVES as often as he thought safe and remove the heavier infested leaves,now when I say infested I mean covered in mite! and when we harvested 2 weeks ago the mite was still present but no webbing on the buds.Its gonna be tough as these little uckers live part of their life cycle in the soil/rockwool.Just remember to have a real good scrub up before starting again.peace,RM.