Hi everyone. I just started a 20 gallon freshwater tropical tank and have been having some troubles. First there seems to be a lack of oxygen in the water. I was led to believe that a filter would do this all on it's own (I have one for a 20 gallon) but others keep telling me that I need an air stone. My tank has been set up for 3 weeks now and the ammonia is still sitting at 1.0 ppm. Is this normal? I have also been getting conflicting information on tank maintenance during cycling and after. Help I dont know what to believe. Thanks in advance.