Stapeley Water Gardens

WHY BUY A POND PUMP?

It is not essential to have a pond pump in all pond features. But there are three main reasons why you might:

1. to operate a feature i.e. waterfall or fountain
2. to operate a filter system, to maintain clean and clear water
3. to aerate the water, maintaining adequate oxygen levels

WHAT IS A POND PUMP?

A pond pump is a piece of equipment that has an electrical motor which drives an impellor/rotor which in turn circulates/moves the water. Pond pumps obviously vary in their output (the volume circulated in any given period of time, usually expressed as litres or gallons per hour but they can vary in other ways.

Surface pumps;
These pumps can operate dry – which means outside of the pond in dry, well ventilated housing. The pumps, therefore have to suck water from the pond via a reinforced hose (suction hose) and then pump it to your fountain or waterfall via a delivery hose. These pumps cannot hanfle coarse solids; therefore a metal strainer (ideally fitted with a foot valve to keep the pumps primed when turned off) should be fitted to the end of the suction pipe.

These pumps are difficult to install, in some cases generate a degree of noise and like for like can often be more expensive to run than submersible pumps. The two big advantages, however, are that they can usually produce more pressure, resulting in most being able to pump water higher and/or to a greater number of features than an equivalent submersible pump. They will also have less drop off in performance as the head increases. Plus the pumps can be stripped down to a greater extent for repair than submersibles.

Submersibles;
As the name suggests these pumps will be placed underwater, either in the main body of water or in a gravity fed chamber. The big advantages of submersible pond pumps are that:
1. there is greater choice of makes and models
2. there are models which cover a wider range of performance than with surface pumps
3. they are easier to install and are ‘hidden’ in the pool or reservoir
4. they are often cheaper to run and buy than an equivalent surface pump
5. they will be totally quiet when running underwater

Whilst it depends on the exact design of the pond pump, in general terms, submersible pumps cannot be dismantled to the same extent as surface pumps. The key moving parts can usually be easily accessed for cleaning or replacement, but if the motor fails it is always a case of replacing the whole motor or pump – which your savings in running costs may pay for!

Induction motors

Pond pumps are designed with one of two basic motor types, with induction being the most common. The basic principle of an induction motor is that the water propelling rotor and impeller is not directly connected to the motor but is spun by the reaction between the magnetic fields created by the motor’s windings and the pumps rotor. The moving parts are lubricated and cooled by water, and the motor can be permanently sealed from this water by a sealed housing. In the case of submersible pumps the whole motor and windings are also vacuum sealed in resin, making the motor extremely waterproof. Apart from the obvious safety benefits it also means that it is practically impossible for the water to damage the motor; and the rotor, supporting shaft and impeller can be easily and quickly removed for cleaning or replacement at home.

Often these pumps have less rotary force (torque) which means that they have less performance especially at higher heads, but are usually cheaper to run. Their design also means they cannot handle solid waste in the water as well as the alternative design, which results in them requiring a good pre-pump strainer. For these reasons the submersible pumps are often called fountain pumps, but this should not describe the limit of their scope due to all their other advantages.

Direct Drive Pond Pumps
In terms of submersible pumps these are also called sump, solids handling or filter pumps. Design wise the rotors shaft is more directly linked to the motor’s windings, and so to keep the motor dry a seal sits around the pumps shaft. To an extent then the pumps life can be determined by this seal. In some cases the seal cannot easily be removed and replaced meaning that the pump will have a more limited life span. This disposable approach is usually reflected in the pumps price and makes them ‘almost maintenance free’. In other cases the seal can be replaced periodically thereby extending the pump life, but this may only be possible by returning the pump to the manufacturer, involving time and money. The advantage of these pumps is that they are often more powerful than induction pumps, are capable of producing more pressure than induction pumps, are capable of producing more pressure for a better head and can handle larger solids, hence why they are sold as waterfall or filter pumps.

Some pumps will handle solids of 4-6mm whilst others will handle 8-10mm. however, there are still limits and if blanket weed or other coarse material is a problem you will still have to use a pre-pump strainer, especially if you are running a fountain, which itself would otherwise clog the solids.

WHAT ELSE SHOULD I CONSIDER?
The obvious thing is the pump wattage as this will determine the running costs. The actual watts used by a pump will vary depending on its running conditions, and different manufacturers may measure wattage under different conditions, but quoted figures are still a useful guide. Pumps also come with different fittings. Most induction/fountain pumps come with useful ‘T’ fitting which can be used to split and adjust the flow of water to two features, for example, a fountain and waterfall. Such pumps may also come with certain fountain jets, so ask yourself are the type of fittings I need supplied and are they suitable? All submersible, induction/fountain pumps will also come with a fine pre-pump strainer, whilst pumps may have a coarse grid inlet or come with a larger coarse cage or additional optional fine strainer. Consider what you are using the pump for then decide which type of pump and strainer will be best for you in terms of ease and frequency of cleaning.

Most pond pumps run off their relevant market’s mains voltage i.e. 230 volts in the UK. Correct instalment and maintenance should make pond pumps as safe, or in some cases safer, as any other mains appliance used in the average home or garden, when also given the appropriate respect. If this installation is unsuitable or you are still unsure, then low voltage (24 volts) pumps are available but only in limited sizes. Our low voltage pumps are supplied with the relevant transformer, which must be placed in a dry, ventilated area (i.e. in the house or garage). The low voltage cable supplied with the pump can then be safely left trailing through the garden, without necessary having to take the steps relevant to mains voltage cable. Burying the cable may, for cosmetic reasons, be appropriate and in either case there are still minor advantages in sheathing the cable in rigid conduit or flexible PVC pipe. Low voltage cable can also be easily extended if required, but lengths above 50metres may result in a voltage drop and therefore poor performance.