Several factors can affect the flow rate of your pond pump:
Head Height: For every meter of head height, which is the distance the water needs to be pumped uphill, there is an approximate flow loss of 1000 litres. Always consider this when selecting your pump. Your pump manufacturer should provide this information in the operational instructions.
Blockages: Blockages within the pipework or the impeller housing can restrict the flow. This may happen if the pump is pulling in larger debris that clogs the pipes.
Valves: A partially closed valve can reduce the flow. Even if the valve isn't fully closed, debris can accumulate around the valve, gradually obstructing the water flow. Try opening and closing the valve a few times to relieve any blockage.
Pipework Fittings: Elbows, T-joints, U-bends, and Y-joints, although useful for directing the flow, can cause flow restrictions. The more fittings you use, the more the flow is slowed.
For more troubleshooting tips, read our full guide on Pond Pump Troubleshooting.