Pond Filter DIY

[Amazing Amazon]

I assume these designs are meant to be above ground filters. ie. the actual canister sitting above the water level for gravity feed. I wonder has anyone designed on that could be buried to keep out of sight? Would it just be a matter of inserting another pump into the actual canister to push the water back up and out?

You can have them either higher or lower (sump style) as long as the water gravity feeds from one end i.e you cannot pump into filter and pump out of filter as you will never get the flow rates exactly the same. If it's not on 24/7 you are wasting your time. Alternatively if it is fully sealed (airtight) you can put it anywhere you like, pump into it, through the media and then back out again. There are lots of these type on the market ( Pond One and Laguna) to have a look at.
Here is a picture that might explain the sump style better