[chrisf]

I am about to set up a large new tank. It comes with a large exernal canister filter. I also have an old spare external filter which I am thinking of adding in to double up the filtration capacity, but only using the one motor.

Doing this would lower the flow rate through the filter due to the extra resistance.

So the question is this...

Is it better to have high flow through a 'small' biological filter or a slower flow through a larger filter mass????

 

[fshfanatic]

IMO, as long as there is even and constant flow through the media you are ok with a lower flow rate.