Conductivity as a general statement in case the pond ever has to be shocked. I plan on keeping records of all the ponds, and the tests might show why a certain thing is happening in the pond.
Sort of like keeping track of the MPG per every tankful on my car. If it drops, there's a reason why. Could be external (snowy/icy conditions) or internal (vaccum line came loose, low air pressure in a tire, etc.)