Simply Koi and More Koi

hi i have a trickle tower lying about its about 2 foot round and 5 foot high and return is a foot above cone to drain ,i have piped it in now to trickle in over bio balls and then rise up in eazy pod and return to pond on three inch gravity .would it be best to leave balls in or take them out as the water has backed up in trickle to hight of eazy so the rest below return should be working as a settlement which is 2 foot deep now all ideas welcome as i like to play and try things.

Since fitting a home made shower with the media above water level I've been able to trap loads of stuff by settlement in the bottom.Nice and easy to see and flush.

So I vote for airborne media and the settlement tank approach.

which is the best media ? and which do you use out there

thanks for all your info