Cool I gotta try this. Maybe a dumb question, but I've never used an acclimation box before. Can all 3 fit in the box at the same time? Do I keep 1 in the box for a day, then bring another up from QT and add to box? I've only added groups together simultaneously directly to DTAdded to DT at the same time? Yes but again an acclimation box would be handy to see if there is any aggression from the existing wrasse.
Should be fine in 20L just watch ammonia levels with ammonia badge.