I have 2 large sponge filters in my 75 gallon South American tank that’s been up for 2 years. It was previously an African cichlids tank. I sold them and bought South and Central American cichlids. Then I had of fighting a diatom algae filled by black beard algae. The filters are coated with bba. And there filtering ability is compromised. Should I just replace the filters or is there a way to fix my problem. At this point I only have 2 medium parrotfish, one adult angel, a small pleco and a Raphael catfish. I don’t want to get more fish with all the crap floating in my tank. Ideas please.