Hey I have a 110 gallon goldfish aquarium which was running great until a couple of weeks ago. My goldfish caught ick then had fin rot which I assume was from the high ammonia levels. I had 5 orandas die on me and only one survivor. The tank has been running almost 5 months prior to this. Filtration is a fluval fx5 stuffed with ceramics and polyfill along with the course filter pads. There is also a fluval 305 that has a coralife turbotwist uv connected to it. It is also stuffed with ceramics and poly. My ammonia tested 2.0 so I did a 50% water change and today its at 1.0. I don't think my tank was overstocked. They were not full grown probably around 4 inches in size. Any suggestions?