dave s

morning all
i am in my second year with a koi pond, now last year i left the pond as it was in the summer and the fish were fine no probs. but this year i lost a couple of fish and i put it down to the sudden drops in tempriture,we have a large lake very close and a number of carp died ther. now i have since been advised to cover the pond in the winter so the question is do i cover or dont i and if the answer is yes what is the best way of doing it.
dave