What To Do With The Pond Filter

You could get a few more extra rocks to hide it from view, but still leaving you access.
Or plant something small and dense to hide it, such as a nice carex grass for all round colour.

I can see, in the top right hand corner of your photo, some green forest bark edging. Perhaps surround it with this and put a plant in a pot on top of it. If you look at my photos I think you will see that this is what I did with mine. Photo No. 26. Sadie

I would also suggest planting something to hide it, if you look at my photo called pond bench, my filter is hidden behind the rhododenron. I know mine is a bit further away from the pond than yours, but you may find something suitable to plant next to it. I did see in Exbury Gardens a wisteria which was left unsupported alongside a pond, quite novel I thought, perhaps you could do that.