You could make a mini bog filter out of a window box planter or just about anything that will hold water that fits your needs.
It can sit on top of your small pond to one side or toward the back. Sort of cantilevered.
The water gets pumped to the mini bog through a perforated pipe covered by pea gravel. The water rises up through the gravel and returns via a low point, a pipe or some sort of weir in the container.
Grow plants directly in the gravel, no pots, which helps with the filtering process.
Many of us advocate using a bog filter because they are very efficient and require little if any maintenance. No rinsing of filter pads. Maybe just a bit of thinning your plants if they get overgrown.
Post some pictures and maybe we can throw up some ideas.
If you need more details on making a simple bog filter, just ask.