Buyer’s Guide to Pond Pumps: Best Rated & Energy Efficient

Yes. Pond pumps are all designed to move water but not all pond pumps have the same features.

Most pond pumps intended for small garden ponds and water gardens are designed to be completely submersible. The motor (magnet and wire windings) and the electrical connection is encased and sealed in an epoxy cube. This makes the pump water-proof and safe to submerge under water. The pump motor is cooled by the pond water.

The other type of pond pump is meant to be out of the water. These are called in-line water pumps because they are positioned outside of the pond but lower than the water line. The electric motor is open to the air for cooling.

A third type of pond pump can be submerged or installed in-line. It can be water-cooled or air-cooled.

In general, all pond pumps have a water flow rating in gallons per hour or GPH. Larger pumps are needed to move more water per hour.

The submersible pumps use the magnetic drive concept.

Magnetic drive refers to the coupling between the pump impeller and the electric motor. The impeller spins and pushes the water. The impeller magnet is surrounded by the motor. The electric motor has no moving parts. It simply creates an electric field that causes the impeller to spin.

Submersible pumps are very simple. Only the impeller moves.

The other style is direct drive.

With direct drive pumps, the impeller of the pump is attached to the shaft of an electric motor. The shaft must be sealed prevent the water from seeping out. Direct drive pumps must be located outside of the pump.

Keep in mind that some magnetic drive pumps are designed to be used in-line only.

Most in-line water pumps are not self-priming. That means they must be positioned below the water line so water is always inside the pump.

Self-priming pumps tend to be larger and are very similar to swimming pool and spa water pumps. They are able to pull water from the pond and into the pump. This means the pump does not have to be placed below the water level.

The type of pond pump you need depends on the size of your pond and what you want to do with the moving water.

A small whiskey barrel water garden will only need a tiny water pump to run a fountain or “spitting” frog statue. A deep koi pond with a big water fall will require a much more powerful water pump.

Pumps are designed to push water uphill. Pond pump flow rates are rated at various head heights. Think of head as the height you need to pump water up to your water fall, ornament or fountain.

As the head height increases, the flow rate and water pressure decreases.

Pond pumps are often rated on their maximum flow rate with zero head. This number may be impressive but is not helpful because all pumps have some type of head pressure they need to overcome.

When selecting a water pump, it is important to know how high you need to pump the water. You need to know what kind of flow rate you want at that head height. If the pump is too small for the head, flow rate will be very low or even non-existent.

Measure the head height and then compare the flow rates provided on the pump box or specification sheet.

It is often recommended to select a pump slightly larger than you think you’ll need. Water traveling through a curved hose causes friction loss and reduced flow.

If you’re pumping water through a submerged filter, you’ll need some extra flow too.

If you find you have too much flow, insert a diverter valve between the pump (under the water) and the waterfall or ornament. The diverted lets you send some flow directly into the pond and reduce the flow rate through the fountain, waterfall, etc.

Pond pumps use electricity. Using a pump that is too large just wastes energy. For the best efficiency carefully select a pump that is only slightly larger than you need.

The general rule for pump sizing is to circulate the entire gallonage of the pond once every one to two hours.

Calculating the right size pump for a waterfall might seem daunting. Don’t worry. Here is a simple way to figure it out.

Select a waterfall pump that moves 100 gallons per hour for every inch of waterfall width. For example: for an 18-inch wide waterfall, use an 1800 gallon-per-hour pump (calculated for the head height).

For a gentler flow, use a 900-1800 gallon-per-hour pump. For a roaring flow use a 2400-3600 gallon-per-hour Pump. These figures can be adjusted for any waterfall.

There are many sizes and styles of pond filters. Some pond filters sit on the bottom of the pond with the submersible pump. The pump pulls water through the filter.

As the filter clogs, the flow rate will decrease indicating it’s time to service the filter. Some pond filters sit outside the pond. Water is pumped into the filter and drains back into the pond. Most pond filters provide water flow suggestions.

Just match the water flow rates to a water pump flow rate (at the calculated head) and everything will work perfectly.

Small water pumps designed for miniature fountains usually come as a kit complete with a fountain head. All you have to do is submerge the pump and plug it in.

If you want to run a small statue you’ll have to run a piece of hose from the water pump to the ornamental statue.

Most water gardeners use flexible tubing to run a hose from the pump to a waterfall or other water features. Black hose is available in many sizes. It is very flexible and blends into the landscape. You’ll be able to route the hose so it is hidden under rocks or around landscaping.

Large koi ponds that have to moves thousands of gallons of water per hour require very powerful “professional” water pumps. In many installations, rigid PVC piping is used to route the water underground to large filters and waterfalls. These types of systems are usually installed by professionals. Some large in-line pumps are noisy and are positioned far away from the pond.

In general, external pumps are noisier than submerged pumps.

Submersible pumps can be placed anywhere on the bottom of the pond. Ideally the pump should sit slightly above the bottom. This protects the pump from becoming clogged with sludge, soil and other debris that collects on the bottom.

In-line pumps are positioned outside of the pond, below the water level. Some pond keepers excavate a below-ground chamber for pumps that do not self-prime.

Professional pond installations sometimes use self-priming pumps, which are placed in a distant pump house to reduce noise and improve the appearance around the pond.

Most pond pumps come with a long, grounded power cord. Just plug the power cord into a nearby electrical outlet. A GFCI (ground fault circuit interrupter)-protected is recommended as a safety factor. Local electrical codes should be followed.

Larger external pond pumps may require an electrician to properly wire the circuit.

Small pond and fountain kits are available that run on solar power. The kits come with a solar collector to power the pump. Solar powered pumps have lower flow rates and are limited to running small fountains.

Since there is no battery back-up, the pumps will only run when the sun is out. Solar-powered pumps are perfect for small barrel ponds that do not contain goldfish.

One of the main benefits of moving, splashing water is that helps oxygenate the water. Goldfish, koi and other oxygen-breathing pond life need aerated water to survive.

Oxygen levels can drop significantly at night and when a low-pressure weather system passes through.

The warmer the water, the less oxygen it can hold.

For all these reasons, it is advisable to run the pump continuously during the season.

Pond life slows down as the water cools. When the water freezes it is important to keep an open hole in the ice to allow for oxygen and other gases to balance out in the water.

A low-wattage pond heater will efficiently maintain a small opening in the ice, allowing fish and other aquatic life to remain alive.