I have heard people say that it is best to slightly overstock an African cichlid tank to cut down on aggression, but since that is not your problem I don't know if that would help you. Your filter is rated for a 110 gallon tank, but it filters 500
gph. I don't really go with the manufacturer's rating for filters, I try to filter my tanks about 10 times per hour (especially since cichlids are such messy fish). Another filter would probably be good in a slightly overstocked cichlid tank, if you choose to go that route eventually, and a canister would probably be best (although another
HOB would be ok too if a canister is out of your price range).