An In Depth Guide to Choosing a Pond Pump

Pond pumps are an essential piece of equipment for all but the most basic of ponds. They are used to run cascades, streams, waterfalls, filters, fountains, spitters and water features as well as helping oxygenate the pond in hot weather. The only type of pond that does not require a pump would be a simple wildlife pond that houses few or no fish.

Choosing a pond pump can seem like a daunting task when you consider the bewildering range of makes and models. This task can be made simpler by following the guides set out below.
What purpose do you require the pond pump for?

1. Cascade, Stream or Waterfall
2. Filtration
3. Fountain
4. Water Features or Spitter
5. Combination of the above

1. Cascade, Stream or Waterfall
Cascades streams and waterfalls require large volumes of water to make them look effective. Every 25mm (1") width of stream will need a minimum water flow of 225 liter (50 gallons) per hour. This amount of water will need to be delivered to the highest point (known as the head height). To enable the high volume of water to be delivered you will have to use an appropriate size hose so as not to inhibit this flow.

The types of pond pumps suitable for this application are similar to filter pumps, please read that section for further information.

2. Filtration Pumps
Filter pond pumps need to be able to pump high volumes of dirty pond water continually to a pond filter system. The impellers need to cope with large amounts of solid matter without becoming blocked. This type of design makes them more expensive than the traditional type of fountain pump. The filter pump is normally housed in a casing that has holes or a grid system to prevent fish or other pond life from being sucked into the impeller. Some makes such as the Hozelock Titan range even come with a Wildlife Protection System to reduce the size of the intake slots. This is useful in spring to prevent small newts and frogs from being in jested into the pond pump.

What Size Filter Pump?
Ponds can roughly be divided into two categories, Garden Ponds and Koi Ponds. Garden Ponds are normally planted with marginal, oxygenating plants and water lilies. They house small fish like goldfish orfe and shubunkins. For this type of pond you will need to turn the ponds water volume over between approximately once every two to four hours. Koi ponds need more water turnover. These fish are normally kept in bare ponds without plants which they invariably eat. If you keep Koi you will need a pond pump that can turn the ponds water volume over once every hour to two hours.

3. Fountain Pumps
Fountains require a high pressure pond pump to force the water through tiny holes in the fountain jet. Unfortunately these holes are quickly blocked by debris particles in the pond so pump manufactures employee several methods to prevent this happening. Traditional fountain pumps (eg. Lotus Baby Otter range) come with a strainer sponge that will require regular cleaning. This should not pose too much of a chore because unlike filter pumps they do not have to be run continually. The Hozelock Cascade, Blagdon Amphibious and the Fish Mate ranges have a fine grid instead of sponges to prevent debris entering the pump. Cleaning this type of pump is simply a matter of directing a strong spray of water at the pumps filter cover. They are also more suited to running filters, cascades, streams and waterfalls. See Combination pumps for more info. Other features to look out for on fountain pumps are telescopic extensions and twist off fountain jets that can be cleaned without breaking your nails.

4. Water Features or Spitter
Water features do not normally contain fish or plants so the water can be kept free of algae and debris by chemicals. This allows the pond pump to be manufactured without a strainer resulting in a smaller more compact design. Examples of suitable pumps are the range of Water Feature Pumps.

Spitters are small fountain ornaments with no jets and can be run by virtually any pump.
Combination Pond Pumps

5. Combination Pumps
Combination pond pumps have tee pieces enabling them to run two applications, normally a fountain and filter or cascade. 

It is a good idea to raise fountain pumps off the bottom of the pond by placing them on a small brick pier, this will extend cleaning periods as the pump won't be sitting in the silt and debris laying on the bottom.

A Word of Caution
Pond pumps with strainer sponges incorporated into their design are only suitable for fountains and small spitters. Fountains in particular need this sponge to stop fine particles blocking up their fountain heads. There are no other advantages to be gained from having a strainer sponge, don't be misled into thinking this sponge is a filter. The sponges will require regular cleaning if they are not to block and impair water flow. Pond pumps are water cooled and if the flow is slowed due to strainer blockage they can overheat and seize up. This type of damage is not covered by the pumps warranty and the pump will not be repairable.

Friction Loss & Pond Hose Flow Rates
Friction loss will reduce the flow on long lengths of hose so if you have to pump water through a length of hose greater than 6m (20ft) use the next hose bore up from that recommended on the chart.

Hose Bore	Max. Flow Rate per Hour
13mm (1/2")	550 litres (123 gals)
19mm (3/4")	1600 litres (352 gals)
25mm (1")	4500 litres (990 gals)
32mm (1 1/4")	7000 litres (1540 gals)
40mm (1 1/2")	13500 litres (2970 gals)