Doesn't sound over stocked. I would just increase the amount of water changes. IMO a change every 2-3 isn't enough. You're better off doing more changes of smaller amounts. It's removes ammonia and nitrite more often instead of removing a lot of it at once then letting it build up again.
I personally do 50% change once a week on 10 gal. Two 25% percent changes a week on my 20 gal. And on my 75, two 30% percent changes two sometimes three time a week. My water stays crystal clear. Not to mention the way a water change schedule like this benefits the fish.
Last edited by ehh; 10-04-2013 at 04:39 PM.