Pond heating
Due to the long winters we have in the U.K. there are some members who prefer to heat their ponds so that they have some control over the temperature. All these temperatures refer to ponds in Cardiff.
There are several electric
heaters available, but as they have to be available for use any time
of the day then you cannot use Economy 7 tariff. For this reason most
koi-keepers use a gas boiler.
This article describes one way to heat your pond with
a gas system.
See also how the heating system on a 6,000 gallon pond has been replaced using a gas central heating boiler.