my boat dos'nt have an aerator system so i freeze a gallon jug of water,fill up my live well as soon as the tour. starts and put the jug in there and takes about an hour to thaw and bring the temp down to the 60 to 70 degree range.i never pump more hot water in because i cant keep that much ice around but i hook up an aquarium pump to an outlet in my boat and leave it on all the time.i've had good luck with this and dont lose to many fish unless i pull a donkey-boy move and crimp the line!