I added an extra livewell to my boat which is 55 gallon and it will pump fresh water in and also runs an recurculation pump with 2 jets, I'am also going to add an small regulated oxygen cylinder to add more pure oxygen to the tank. By pumping in fresh water in you can keep the water temp in the livewell close to the temp of waters the fish is use to.
Most of us believe that running their aerators on the automatic timer was sufficient for as many fish our tanks can hold. Obviously, livewell design, size, and efficiency varies. Human variables and weather conditions, particularly water temperature, affect water quality and fish mortality. If the lake or river is over 75 degrees, it's impossible to keep the dissolved oxygen level in your livewell much over 5 or 6 ppm with no fish in it.
By adding pure oxygen to the tank you can boost dissolved oxygen over 20 ppm, with just a few cents per hour to run.
But there is danger issues with running pumps in oxygen enriched water. Any electrical device used in oxygen enriched environments must be certified specifically for use within oxygen enriched environments. The risk of ignition and fire is greatly enhanced when electricity is used improperly within oxygen enriched environments.
My tank is set up so that I can pump fresh water to the bait tank and livewell to bring in fresh water and I would not run the recirculation pump when pure oxygen is introduced.
Sorry so long.