Despite it having no flowing water into or out of it, the pond is large enough to have evolved it's own wind blown 'current' - plus the leech and the flatworms will get anything that isn't a water snail or a daphnia or a water flea.... not had a problem with mossies at all.

Snails were particularly lively yesterday - lots of them all stuck together in pairs... even the leech was looking sprightly!

LTS