Yesterday I did the first cleaning and partial water change for Gizmo. I picked up the small gravel cleaner at PetSmart on Saturday and you guys were right, it worked great. I did get some dirt out in the bucket but noticed what I stirred up and floated in the tank was like small sheets of something. Remined me of flake food but I feed the pellets. Just wondered what it could have been. When I finished I noticed Gizmo just swimming side to side along the back of the tank. He didn't just swim and glide like normal. As I watched, I realized that I was so worried about getting the temp of the water I was putting into the tank to 80 degrees that I forgot to put the drop of water condiner in it. So I sweated it out for a few minutes. His tank is five gallons and I took out and replaced one gallon. Thankfully in a few minutes he was back to behaving normally, geez I was scared I might have killed him on the first cleaning. Do you think a water change of one gallon a week is sufficent?