I'll jump in.........
With no particular reference to the design you show, there are two waste issues to deal with:
1. Solid waste
2. Dissolved organics
If find it best to take separate approaches to each challenge.
I like to move all water through a micron bag filter first. In that way I can completely eliminate solid waste (daily if needed) by emptying the bag (it can be hosed out, washed while another is used, etc.). Getting the solids out of the system goes a long way to improving water quality. With a canister all the waste just sits in the canister until you remove it. As a result, the bio-pressure on your filter is greater and nitrate production can be significant. You could certainly clean a canister daily, but it would be difficult. So, I wouldn't use a canister at all if it was my choice.
Once solid waste is removed, you only need to be concerned with dissolved organic compounds (DOCs). Water can be trickled over bioballs or something similar (I prefer non-porous media though). Several designs are fine in that regard.
I am going to assume you cannot gravity feed water out of your pond into a sump. So, if it were me, I'd use a couple of very large submersible pumps to move water out of the pond and into a micron bag. The cheapest way to do it would be to use a bucket with a lid. Cut a hole in the lid slightly smaller than the lip of the bag, and cut out most of the bottom of the bucket. The bucket could be positioned above another bucket that is full of bio-balls (becoming a non-submerged trickle tower). The water trickles into a sump and gravity feeds back to the pond.
If you can gravity feed the filter (which would be best), simply have the return pumps in the sump. Also, there are many ways to make a more "polished" presentation, but they are all along the same lines.......
Hope that helps!
