Water Pumps for the Garden Pond
If you want to move water from one place to another, then you need to invest in a pump.
The performance of any pump is affected by water temperature, pipe width and length, any angles in the pipework or connectors and the number of water features connected to the pump. With specific features there are such factors as the intended heights of fountains and falls, and the volume of water. All of these can bring about friction loss, which will affect the ‘vertical head’ — that is, the maximum height to which the pump can deliver water. For all of these reasons, it is generally advisable to buy a pump that slightly exceeds the maximum amount of flow that your feature(s) will require.
To calculate the right size of pump for your pond, you first need to ascertain the volume of water in your pond or feature. You will need a pump that can circulate a volume equivalent to the total volume in your pond every two hours. All good makes of pump will declare on the packaging the quantity of water that they will move.
The most common type of pump is the submersible pump, which sits within the body of water in the pond, attached to a hosepipe which carries the circulated water up and away. Unless a particularly powerful pump is required, for a high waterfall for example, this type of pump is the best option.
Submersible pumps can be relatively cheap —because of mass production — but you get what you pay for, and the cheaper models have less of a life expectancy. Never let a submersible pump run dry, as this will damage the motor.
A pump that is designed to be used on dry land is the surface-only pump. This has the advantage of being extremely powerful, so water can be pumped over large distances, or very high for a spectacular fountain display. It should be housed in a dry, well-ventilated area such as a garage or shed, so as to avoid the problems associated with mixing electricity with water (although there are in fact diesel- and petrol-powered versions). Because surface-only pumps are not submersible, they can be stripped down and repaired more readily. These pumps are, however, relatively expensive.
Neither do they come with many of the standard ‘extras’, such as connectors, strainers, hoses, and so on. These will be necessary components to the finished system, and all add to the cost.
Dual purpose pump systems
This type of pump can be used as either a submersible or a surface pump. Some makes need to be housed at a lower level than the water level, so a separate tank is required. However, these pumps offer the flexibility for you to change your mind about their position and use.
Of course, if you want to operate features such as a waterfall and fountain independently, fitting one pump for each feature will often prove more satisfactory.
Calculating the volume of your pond
To determine the volume of water in your pond, measure the length, width and depth of the pond in feet and multiply these together. Multiply the figure by 6.25 to give the volume in gallons.
For a circular pool, measure from the centre to the side and square it: multiply the result by 3.14. Multiply this by the depth of the pool (in feet) and multiply the result by 6.25 for the volume in gallons. This equation is simpler than you think!