"GrannyGrump" wrote in message
...

we have tried putting a tennis ball in the centre of our garden pond
to stop the water from freezing however, with the bad weather recently
this hadn't worked. Can anyone suggest an alternative?

Floating pond heater. Get one at a farm supply store, such as Tractor
Supply.

Plan B: put one into your filter (if you run one).

Less wasted heat loss and you know it's not just heating a small area.

--
Brian
"The wind, do you hear it? It says 'Hel ... looo'"