Pond heater and frogs

[yorky]

We've had the pond for many years but no longer have fish in it. Pump and waterfall installed and normally kept running for a couple of hours each day throughout the year.
However, in the current weather, the waterfall froze up and so I switched the pump off and left the small floating pond heater in the pond to keep a hole free to release any build-up of gasses.
When I went to check the pond this morning (in the dark at 6-30) if saw in the torchlight a great number of frogs on the bottom of the pond, but immediately below the floating heater.
QUESTION: Should I leave the heater in the pond (it's on a timer so as to use Economy 7 tariff) or should I remove it and let the pond freeze over?
All opinions gratefully received.

[tom00_uk]

if its just a waterfall that the pump serves and not a filter as well then turning off for winter is a good idea as it will reduce the cooling experienced by the pond

keep the timer running as you have been, they will have no harm from a small hole being made for gaseous exchange, its not heating the hole pond just enough to keep a small area open