I've been doing some browsing.....until digging is complete I do not
know exactly what volume the new pond will be - but from my indoor
fishkeeping experience I do tend to over-filter.

Aquatics Online UK have a clearance sale on some of the older model
Hozelock filters that include UV as well. The model I am looking at is
the 1000 gall version (although I suspect the pond will end up a lot
less than that) - it is a snip at £53. The other one on offer is the
Ecomax at £65. This compares with almost double the price for the
current range.....I can't actually see any difference in the specs of
any of them so thought I'd ask if anyone else has used any of these
before I hit the "Add to shopping cart"

TIA
Gill