Thanks
I've had a *lot* of time to think about all of this stuff, although I've almost certainly screwed up all over - there's just so many small details that turn out to be ... ahem... not so small.
Case in point. I had originally expected to mount the UV system horizontally, suspended from the roof of the sump. It turns out you're supposed to feed water vertically downwards into the UV, not vertically upwards... That means I'll have to mount it vertically instead, which doesn't fit into the sump. Fortunately there's a side to the stand which is pretty much out of sight in the corner of the room, so I can just put at the side of the stand there...
I guess I ought to have downloaded the manuals and read them first. Oh well, live and learn
Thanks for the kind words
Simon