Today, I noticed that my water in my aquarium was a little foggy, even though I don't have or never had any fish in it. (it's brand new). It's been running for a week. I talked to the guy at the LFS and he said that my water went "stale". Has anyone ever heard of this? He told me to change out all of the water with fresh water, and try to add fish as soon as possible. Does this make sense? Why did my water get cloudy?