get some climbing perch... they do eat alot of fish poo...yes it does...cuz i have 6 of those and 1.5 ft or silver aro and 8-9 inch of oscars....mine is like crystal clear...
about the carbon + bio media it does help thou ..
i have live gravels bio media and carbon at the bottom of the tank and inside of the filter.,... as for me it does make diffs..
I use the media the filters came with for the aq110, as for the fx5 i just run the sponges and ceramic rings it came with. no carbon in any. i have never replaced the mech filtration material, been about a year
I had the same problem tried every thing then tried having my light on for less time through out the day and BAM! Problem solved, guess it was algae related. GL