Email me and I'll give you the email for a lady that I bought mine from. She is looking to shut down her tank and find homes for her remaining ones.
grundsau26@hotmail.com
There are a couple of people in the Capital cichlid association that breed convicts. http://www.capitalcichlids.org/ They should be close to you so you don't have to ship them. I have 3 extra males: 2 jumbo blacks, and one large pink. You can have one for free, but the shipping will be about...
A diatomaceous earth filter would do the trick. If you use a Marineland Magnum filter you could try using the micron filter without the diatomaceous earth.
You could also contact some tank maintenance companies. They usually do the maintenance on really big aquariums. Perhaps one of their customers would have the room.