I use to raise tropical fish. If you take regular tap water and put it in a container of some kind, I used old milk jugs, and let it set with the cap off for 2 days the chlorine comes out and you dont have to use any kind of water conditioner. So when you take the water out of your tank just replace it with the jugged water. It works fine. Once I get my minnows to the lake the first thing I do is pour out 1/4 of the water in the bucket and replace it with lake water. Do this about every ten minutes untill all water is replaced. This gets them use to the lake water and you will have livelier minnows on your hook. I keep all but about a dozen in the lake in a removable bucket and the others in a bucket in the boat. The more you keep in the boat in a bucket the more oxegen they will use up and they will die quicker. When I need more I just pull some out of the removable bucket. Most of the minnows stay alive this way. Have been out when it was over 100 deg and been able to keep my minnowqs alive this way.