J
jaws7777
got the answers 
I asked him how he set up and ran his filters and this was the response:
Very low flow rate, maybe 50 liters per hour perhaps even less. This would be termed an anaerobic filter
Two canisters in fact and this is fed by my central pump which feeds everything, bliological filter and all the tanks, and then it has this side arm which flows very slowly over these two canisters.
Optimally, for it to work even better, one should feed such filters with organic substances such as alcohol! I do not do this so the filter must be running sub-optimally. What this filter does do though is it keeps my nitrate levels below 10 mg per litre.

I asked him how he set up and ran his filters and this was the response:
Very low flow rate, maybe 50 liters per hour perhaps even less. This would be termed an anaerobic filter
Two canisters in fact and this is fed by my central pump which feeds everything, bliological filter and all the tanks, and then it has this side arm which flows very slowly over these two canisters.
Optimally, for it to work even better, one should feed such filters with organic substances such as alcohol! I do not do this so the filter must be running sub-optimally. What this filter does do though is it keeps my nitrate levels below 10 mg per litre.