You should always bare in mind, if a pump is being installed in a fish pond it must have a pre-filter or filter cage. If a filter is not used, warranty may be voided as a result of the excess wear which may occur to the pump unit. The alternative is to use a Vortex style pump (DWP Series)which is designed to tolerate dirtier water.
Pumps for Waterfalls
Try simulating a flow of water over your waterfall with a garden hose, with someone adjusting the tap until the desired effect is achieved. Next, use a 10 litre bucket and reading a watch with a second hand, transfer the hose into the bucket and time how long it takes to fill the bucket without adjusting the tap. Divide the time in seconds to fill the bucket into 60 and then multiply by 10.
Example: 20 seconds to fill a 10 litre bucket. 60 divided by 20 = 33 x 10 litres = 30 litres per minute. Next you need to measure the height of the waterfall above the pond water level and check the pump performance chart to determine which pump is suitable for the application. Should you require a fountain spray add 15 – 20 litres per minute to the result you obtained from the above calculation. Don’t forget that if a pond is to hold fish, a biological gravity or pressurised filter will be required and an allowance must also be made for the filters required flow rate. Note: an optimal system should contain both biological and UV filter to maximise the management of the water system.
Pumps for Statuary Features.
First check the overall height of your statue from the water level to the top. As a rough guide, allow 100 litres per hour for every 100mm of statue height