Isn't this the tank that's very overstocked with all of the catfish? I'd say the best way to control is to move a lot of these fish! Sorry, but when stuff like this starts happening, you really have to consider your stocking-to-volume ratio. Your water changes are about the best thing to do. I wouldn't add "chemicals" per se, such as in Ammo-Lock or any of that stuff, but I would try and get a hold of some seeded media. You wouldn't happen to have some extra HOBs running that you could transfer over, would you? Second best thing would be to add one of the Bb-in-a-bottle that actually works -- Dr. Tim's One-And-Only or Seachem Stability. Also, you'll need to figure out what could have happened to throw off your cycle... you know, the usual suspects... over-cleaning, over-feeding, using tap water, etc., but I think your stocking is an issue, and if it's not right now, it will be next month, or whatever. You've got a lot of fish in that tank.
Cleaning the filters may have been a bad step...