If you keep the pump on recirculate all day long the heat from the pump will heat up your water. You need to flush the livewell with fresh lake water several times during the day. It will eliminate any heating from the pump and flush out any ammonia. In my 492 when I run I switch to recirculate. When fishing I turn the valve, not the timer, to auto which brings freshwater in. The only time I wouldn’t want to bring freshwater in is if I’m in an area where the water is stagnant or full of debris (like duckweed) that could clog the pump. Anytime I’m fishing in open clean water I bring freshwater in. Always run the pump continuously. No timer!