Maybe run a fluval 405 or the equivalent from eheim in addition to one of the ac110s if you can fix one, otherwise just get an fx5 and be done with it.
Better would be a fx5 canister or a couple of xp4's
Best would be a sump around 30 Gallons with a pump that would turn the tank over 6-8 times an hour.
But for right now---
If you have 1 ac110 with a burnt motor and one with a cracked case. Then switch the motor from the cracked one onto the good case and get a filter running.
How long can a 10 inch RTC, 5 inch paroon, and 2 12 inch clown knifes live without a filter... I cracked my Aqa clear 110 and now i have no filter until tommorow.. Can they survive without a filter for 15 hrs??