Our pump is in the pond but the filter is outside...
It is in the tall wooden structure behind the waterfall. It is a proper bought filter, not homemade. Water sprays in through holes in the pipe, like a spraybar, then trickles through foam and other media before returning to the pond over the waterfall. We had to drill bigger holes in the underwater end as it kept clogging too quickly. Raising it several inches off the bottom helped too :lol: