Planter box filter setup

[innovest_11]

hi all

i have a planter box in my balcony, which i use to keep my koi. I plan to just put in 10 bags of filter material into the planter, total about 25 kgs, into one corner of the planter area, without any partitions. Maybe i'll put the filter material into those toyogo box with lots of holes, then put them into the planter area.

I'll put in a air pump to pump air into the planter box.
But do i need to put in water pump to pump water from one corner of the planter box to another corner of the planter box where the filter material is? Because the filter material is already in the planter box, do i need to use the water pump to circulate the water?

Any comments with the above setup?