Pond Pumps Buyer’s Guide.
Regarded as the heart of the pond, the pump (like the heart) must be the most reliable part of a garden pond. We expect a pump to work 24 hours a day and every day of the year in temperatures ranging from near-freezing to perhaps over 25oC, with both the life of our pond and its appearance depending on a reliable pond pump. Because of its partnership with a pond filter, once installed, a pond’s health relies totally on a pump, and over recent years, pump performance and reliability has increased dramatically in order to meet our increasing demands.
Why have a pump?
A pump is not essential for keeping a pond clear and stocked with fish but by adding a pump that circulates water through a filter, you are able to keep more fish in your pond and guarantee clear water (when using a UVc).
It can be very daunting when choosing a pump when you are presented with a vast array of different pump makes and models, each with their own features and performance claims. On the positive side, by virtue of the choice available, it makes it far more likely that you will find the pump that is particularly right for your pond.
What to look for when choosing a pond pump.
Before you can choose the pump that is most suited to your pond, you need to know your pond’s volume (in both gallons and litres) and your anticipated stocking levels (light, standard or heavy).
You also need to measure any additional ‘work’ that your pump will have to do, such as pumping up a waterfall (measure the vertical distance (or head) from the pond’s surface to the top of the waterfall) or a fountain or ornament. Any additional ‘head’ required of a pump will reduce its overall turnover.
1. Pump Flow Rate
A useful guide when choosing a pump is to find one that circulates the volume of your pond at least once every 2 hours.
Most pumps are sold with very flattering specifications, perhaps stating that a particular model will pump 1000 gallons per hour. This is probably measured at the pond surface without any restrictive pipework or fittings attached. As soon as a pump has to move water vertically, the turnover of that pump is reduced. The greater the head, the lower the turnover. If a pond has a volume of 500 gallons, it requires a turnover of 250 gallons per hour. If that same pond has a waterfall that is 3 feet high, then a suitable pump would be one that provides a turnover of 250 gallons per hour (minimum) at 3 feet of head, which will mean choosing a more powerful and more expensive pump than at first expected.
What volume is required for a waterfall to look realistic?
For a waterfall to look realistic, with the full channel width covered in flowing water, sufficient water must be delivered by the pump to the top. A useful rule of thumb is that an average running tap represents approx 200 gallons per hour. A flow of 500 gallons per hour is usually required for a waterfall 6″ wide. If a pump is not able to deliver this flow, then a waterfall will be a trickle rather than a cascading flow. So returning to the example above, if the waterfall is 6″ wide, then the pump must be able to deliver 500 Gph at 3′ head for the waterfall to look realistic.
2. Other performance factors
a. Solids Handling. Garden ponds present some of the most demanding environments in which pumps are expected to perform. Let’s face it, we want to install a pump and forget about it. In response to our reluctance to get our hands wet for the sake of pump maintenance, pump manufacturers have re-engineered their models to handle solids. This means that rather than clogging up with debris as they may have done before, they simply pass this debris through to the filter. Before buying, check that your pump will handle solids.
b. Pump protection Many submersible pumps are fitted with additional safety features. Float switches are a safety back-up which prevents pumps from burning out should they run dry. Should the water level within a pond drop, then the change in angle of the float switch will cause the pump to switch off. An additional safety feature found in many pumps is a thermal cut-out which also switches the pump off should it over heat. This will also protect the pump should it ever run dry.
c. Variable hose fittings. You may be buying a pump up to replace or upgrade your existing model. If so, it may be worth checking that the new pump is supplied with a stepped hose-tail on the outlet. This will allow it to fit a range of hose sizes, and hopefully yours that is buried beneath your rockery and waterfall.
3. Running costs – The Hidden Extras.
As a pump is likely to be used continuously, the running cost is a significant consideration when pricing up a pump for a particular pond. Power consumption is measured in Watts with the greater the figure relating to a power-hungry pump. The wattage does not necessarily relate to the overall performance of the pump as many efficiencies in design and construction enable low wattage pumps to outperform pumps with larger motors. For example, when comparing 2 pumps each rated at 500 gph, one may be a 65W model while the other one may be a 100W model. Which would you choose? The difference in running costs over the years could amount to the price of a new pump. When the running costs are forecasted across the 3 years of guaranteed life of a pump, you are able to get a true picture of the real cost of that pump. (See Table for an approximate guide)
As we have demanded more from a pond pump, they have become more rugged and reliable. Consequently, most pumps are now sold with a free extended warranty of 3 years, with some models this year carrying even a 5 year guarantee! This is a measure of how reliable (and competitive) pond pumps have become. With standard care and the use of correct pipework so as not to produce high back pressures, then such guarantees can easily be exceeded. Pumps are likely to be more temperamental if they are switched on and off rather than used continuously and problems can also occur with pumps becoming blocked with debris or blanketweed, choking the impellor and leading to a burn-out.
Most pumps are fitted with foam or perforated plastic pre-filters to prevent impellors from becoming blocked, but these can reduce pump performance even when only partially blocked. Self-cleaning pre-filters are available as a remedy for this common blocking problem and as mentioned earlier, pumps that will handle solids up to 10mm are now available on the market.
In summary, there has arguably never been a better time to buy a pump. There is a huge range to choose from, most of which offer us the latest engineering and efficiency, giving us complete peace of mind. Simply take your pond’s measurements to an aquatic store and by checking for the factors above, you are sure to leave with the best pump for your pond.