I too have added ice from my cooler not thinking about chlorine in the ice or water temps, but after watching a u tube video I doubt I will anymore. Ok lets say the water temp is 70 and you know cooler water in the minnow bucket keeps them lively, so you add a couple handfulls of ice, so now they are in maybe 45 degree water, ask yourself what happens when a minnow gets the shock of 25 degree warmer water? = dead minnow