every time I have tried this "floating a ball on the water" trick the ice
just formed under the ball pushing it up above the surface.
I have a UV filter which provides enough warmth via the bulb to keep the
pond from freezing.

Andy P


"Sad Sid" . wrote in message
...

"Franz Heymann" wrote in message
...
Just break the ice regularly so as to expose some of the surface of the
water to the air.

Franz

Be very careful doing this - you could easily stun the fish. Best practice
is to float a football on the pond. If it ices up for more than a day,
lift
out the ball to expose a hole. If you wish you can then increase the size
by
breaking the ice "up" rather than whacking it down.

In very cold winters I dangle an ordinary aquarium heater just below the
surface. It's sufficient to maintain a permanent air hole.