These pond heaters are designed to go inline in your pond system between the pump & the filter. It comes with a 60.5mm adaptor for standard waste pipe 50mm solvent weld connector & stepped hose tail connectors for 25 32 & 40mm hose. As the water from your pond will be running through the heater it is the most effective way of heating your pond in winter. Koi keepers may also be interested in keeping the heater running through the Spring & Autumn season to encourage growth in their fish. Please note that solvent weld adhesive is required if using rigid piping. This is available 1k W is suitable for up to 10000 litre ponds. 2k W is suitable for up to 20000 litre ponds 3k W is suitable for up to 30000 litre ponds