Hi. I posted about a week ago about the loss of three of my five Koi due to a drought that drained my pond. I managed to save two and am keeping them in a 50 gallon tank until the rains return. My questions is about water changes as I have never had to deal with them before. I did a partial water change about three days ago and the water is already getting cloudy and starting to have an odor. How often should I do partial water changes? I intitially added about a bucket and a half of native pond water. One Koi is fairly large. About a foot and a half and at least 3lbs. The other is about half that. Thanks.