We have a kockney koi black box filter for our pond with a 25W UV unit. The UV tube is now 3 months old so well within its lifespan and yet it has suddenly stopped working. The greener water was the give away so I went down the garden after dark and sure enough, no sign of the distinctive glow at the end of the unit.

Never had a tube fail on us before with this box, so is that the most likely cause do you think? Perhaps the connectors have failed? We have had to replace those in the past when changing the tube as they seem to drop to bits after a while.

A complete UV unit to replace it is about £70. Any thoughts? LL.B (Hons) - University of Derby
LOT (Lord of Time) - University of Gallifrey

Spoken to local pond centre and we need a new electric box for £60. Sounds easy enough to fit  LL.B (Hons) - University of Derby
LOT (Lord of Time) - University of Gallifrey