When selecting a pond filter pump, it's important to remember its main function. It sounds simple, but the need to remove debris from a pond and maintain a continuous flowrate that will turn over the volume of your pond at least once every two hours, put great demands on a pump. Because of these demands a filter pump that is specifically designed for the purpose will ultimately be a more cost effective choice.
Traditionally, the main types of filter pumps that were available were known as Direct Drive” or “Sump Pumps”, such as the currently available Draper or Hippo pumps. Pumps of this type were often used in the construction industry to pump dirty water out of ditches or holes in the ground, as they are cheap to purchase and the large inlet holes ensured that they did not block up. Although these pumps do produce high flowrates, they also have high power consumptions and as they are not designed to run 24 hours per day, they have limited life spans.
Over the last 10 years, the major manufacturers within our industry have designed specific filter pumps which can still produce the required debris collection and flowrates, but with a much lower power consumption and longer life span.
What To Look For In A Modern Filter Pump.
The main features to look out for in a modern filter pump are:
- A filter pump should be housed in a plastic cage with large holes to allow particle to pass through.
- A filter pump should be designed for continuous use.
- A modern filter pump should have a power consumption which is as low as possible.
- A purpose designed filter pump should have a guarantee of at least 3 years.
Which Filter Pump should You Choose?
As with most products, to some extent “you get what you pay for”, when picking a filter pump, you will find pumps of the same size at very different prices. This is usually relative to the power consumption and guarantee period.
If you decision is based purely in terms of purchase price, you should divide the purchase price of the filter pump by its guarantee period. This gives you a cost of owning the pump per year (assuming the pump fails the day after the guarantee expires). As some filter pumps are supplied with a 5 year guarantee. It may be more cost effective to pay a higher purchase price for a longer guaranteed pump.
But don’t forget running costs !!!. Remember to check the power consumption of a filter pump. If the filter pump you are looking at has for example a 50 watts lower power consumption. The filter pumps will consume 50 watts per hour less for 24 hours per day, for 365 days per year, for at least the length of the guarantee period. So again a cheaper filter pump may not be the best value option over the life span of the pump.
Which Size Filter Pump Should You Choose?
The size of your filter pump is a more complex issue. The general rule is that a pond filter pump should be sized to pump at least half of your pond volume per hour. However when it come to real life situations, there are other factors that should be considered.
For Standard Pond Set-up's
- System Compatibility
- Vertical Head Lift
- Pipe Size
Additional Factors For More Complex Set-up's
In most standard pond situations, manufactures assume that you will have around 3 - 4 m of flexible pipe which will be installed with a minimal number of bends. So you need to take the first 3 factors in to consideration when picking a filter pump.
- Pipe Length - Friction Loss
- Pipe Bends - Friction Loss
Although the general rule is that you need to turn the pond volume over once every 2 hours, it is essential that the filter pump flowrate does not exceed the maximum flowrates of the other equipment in you filtration system. If a you exceed a pond filter or UV's maximum flowrates, you may damage the unit or in the case of some filters, cause them to overflow and eventually drain the pond.
Vertical Head Lift
The vertical lift is the height difference between the surface of the pond and the top point that will be pumped to. Every pump has a performance table which will tell you what flowrate you can expect at any given height. So as an example, if you have to lift the water to 1.5m above the pond surface, a pump which might state a maximum flowrate of 6000 lph may only produce 4300 lph.
When connecting you equipment together, most manufacturers will provide "multi- stepped hosetail" to allow the use of different sizes of flexible pipe. Although smaller pipe sizes are cheaper and easier to hide, they will have a very big impact on the flowrate a filter pump will produce. As a rough guide, you can expect the flowrate to drop by approximately 25% for each pipe size reduction from the largest size that can be used. So if a pump will accept a 40mm (1½") pipe size, but you fit a 20mm (¾") pipe, you can expect to see approximately a 75% reduction in the pumps performance. So the golden rule is to always use the largest pipe size a filter pump and you other products can accept. Anything smaller and you will have wasted money on the pump you have purchased.
More Complex Set-up's
In some situations, long and complex pipe runs can not be avoided. These require more complex calculations to correctly predict the correct size of filter pump required. In this situation one of our highly experienced technical staff will be happy to help, give us a call on 01778 341199 to have a chat.
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