I have two tidal 110 hob filters for my 75 gallon tank. I have four fish. One 5 inch trigger one 5 inch fox one 2 inch sail fin and lastly a blue spotted puffer. So I am over filtrated and under stocked. Three weeks ago I noticed my water smell. I have no invertebrates.!NOTHING a changed. My tank is a year old. I’ve been testing since and my ammonia is constantly between .08 and .20. I did a 60% water change Monday and I’m measuring at .14 today. What is going on