I have an aqueon 20 gallon hexagon tank with an aqueon quietflow 50 gallon filter. The tank has been set up since a week before Christmas, and I've had fish in it since New Years eve. I have one cory cat (I know they're not supposed to be alone, but I'm hesitant to add fish due to cloudy water) 4 platys, and 1 molly. I upgraded the filter from a 20 to a 50 around the first week of January, and I didn't keep the old media, so I know I basically kicked my tank back into a new cycle. I had trace amounts of ammonia and nitrite up until last Thursday, when it finally went back down to zero for both ammonia and nitrite. my pH is about 7.3. The water has been pretty cloudy for about a month, and I thought it would clear up once the ammonia and nitrite went down but it hasn't. A local pet store that specializes in aquariums told me to change the carbon filter, and that it'd be safe to do because the good bacteria is stored in that blue bio grid that comes with aqueon filters. She said this would clear up the cloudiness, but everything I've read online says to just rinse it. What can I do to clear up this tank because I would really like to add a couple new fish and have a good looking tank! Thanks.