I've been having a problem with ammonia in my tank for about a week or so now. I was sure it was from a media change in my filter. It was testing just over 1.0. I was doing water changes daily and could not bring it down. I finally tested the water straight out of the faucet and it tests just shy of 2.0. Within the past year, the village where I live changed over the water system to filtered water from the river, but its not like city of Chicago water where they use UV sterilizers, they add chemicals for sterilization. I visited the pet store in the area and there are a ton of ammonia reducing additives that are "safe for all tropical fish" but with rays you can never be too careful. Has anyone out there had this problem? Any suggestions?