I keep forgetting you run aquaponic systems. You could very well be someone my company would like to talk to within a year or so as we design our aquaponics production shed.

As to internal pressure - the turgidity of the plant, how rigid it is due to internal water pressure (silicate reinforcement notwithstanding.) Magnesium is the other regulator to this.

The chloramine is much more dangerous to the fish than the chlorine, however. Actually this depends, saltwater fish can handle the excess chlorine amounts. Freshwater fish most certainly can not.