alas I seem to have gained some light fungus on a couple of my koi, (the
cotton wool like patches), I have brought some "treatment" (interpet Koi
anti fungus and bacteria). the instructions tell me how much per litre,
but don't mention if I should turn off the UV, it does state I should keep
pumps and filters running,

would keeping the UV on kill the effectiveness of the product?

LL