I use the water that the bait store puts in the bucket. I also use one of those small aerators that uses 2 D cell batteries. It may be that there are to many minnows in the bucket cause the guy is pretty fair about giving you more than you pay for. If it is really hot out I cool the water down with ice. Maybe the ice has enough chlorine in it to do the damage. I don't use very much and only cool it down a few degrees.