We have put together this guide to help you through the process of selecting the right pond pump for your outdoor pond or water garden. Below you will find information on pond pump ratings and the various types of pond pumps.
There is a wide selection of pond pumps available, but all are rated the same way. The abbreviations GPH or LPH, meaning gallons per hour or liters per hour, are used to measure the maximum performance of pond pumps. Another common term used when rating the performance of pond pumps is maximum head pressure or head height. Head height is the measure of resistance to flow caused by friction and gravity. Pond pumps will have a maximum head pressure rating, this is an approximation of the distance in feet (both horizontally and vertically) that a pump can push water though your plumbing. As head pressure increases, pump performance decreases, knowing the head pressure of your application is critical to your pump selection.
A pump's maximum head pressure rating is the point at which the pump will no longer function. The effects of gravity on head pressure is very simple; every vertical foot of distance the pump moves water equals one foot of head pressure (1:1 ratio). The effects of friction on head pressure is a little more difficult to calculate. Every ten feet of pipe through which water will travel horizontally contributes 1 foot of head height (10:1 ratio). Every 90 degree turn in your plumbing will contribute 1 foot of head pressure (1:1 ratio). For example: if you were to install your pump 30 feet from the top of your waterfall, which was 4 feet above the pump, with two 90 degree elbows in your plumbing your water feature’s head height would be 9 feet (horizontal distance contributes 3 ft, the vertical height contributes 4 ft, and the 90 degree turns contribute 2 feet). In this example, you would want to choose a pump that has the desired GPH rating at 9 feet of head pressure.
Tubing size is also an important factor in accounting for head pressure loss, in general you should never reduce the diameter of the tubing below what the output size of the pump is, this will drastically increase head pressure, and reduce pump performance. For maximum pump performance, using the largest tubing that is practical is the best choice.
Types and Terms
A pond pump is essential to pond maintenance. Most ponds require some sort of pump to power a filtration system, water feature, or for simple pond water circulation. Many types of pond pumps exist and each has its own unique features and applications. Below are some common pond pump types, as well as common pond pump descriptions.
Statuary Pond Pumps:
By far the most commonly used pond pumps, these submersible magnetic, or mag drive, pumps use electromagnetism to rotate an impeller and force water out. This method of forcing water is usually among the most energy efficient systems. Perfectly safe for fish ponds, these non-oil lubricated pond pumps are available in sizes to fit most ponds. They are ideal for powering everything from a small pond spitter to a waterfall system. They are easy to maintain and to service. Statuary pond pumps or magnetic drive pumps are an excellent value in reliability and energy efficiency.
Direct Drive Pumps:
Designed to power water to greater head heights, Direct Drive Pond Pumps utilize electric motors that physically turn the pumps impeller with a drive shaft. Direct drive pumps are usually more resistant to head pressure performance loss, but require greater energy demands. Direct Drive pumps can be external or submersible in design. Some submersible Direct Drive Sump Pumps are lubricated with oil, making them unacceptable for fish ponds, though many recent models use a type of lubricant that is completely fish safe.
Submersible Pond Pumps:
Submersible Pumps are designed to operate completely submerged in your pond, and many need the water to keep them from overheating. Many submersible pond pumps include integrated pre-filters or filtration systems, as well as pond fountain systems. Submersible pond pumps are very easy to install, however they must be retrieved from the pond to perform maintenance. The unobtrusiveness of submersible pond pumps allows you to easily conceal them; and they won't disrupt your outdoor activities with unwanted noise. Some Submersible pumps can also be use in-line outside of the pond, though this is usually not their ideal application.
External Pond Pumps:
External Pond Pumps or in-line pumps, are typically installed on large pond application, and offer maximum performance when high flow rates and head pressure are required, such as large waterfalls or Pressurized Filters. External Pond Pumps tend to be more difficult to install than their submersible counterparts, but generally require less routine maintenance. If your external pump is not self-priming, extra measures must be taken to protect your pump in the event of a power outage, with the use of check valves. External pond pumps can be more noisy, which could disturb outdoor activities. A typical swimming pool filtration system uses External Pumps.
Debris Handing or Solids Handling Pumps:
This term is applied to submersible pumps which are specifically engineered to handle large debris loads with little risk of clogging, or damage to the pumps impeller. These pond pump powerhouses can continue to move water through difficult conditions. Debris handling pumps, also sometimes referred to as waterfall pond pumps are usually more powerful and more expensive then their counterparts, but are a good value do to the minimal maintenance required for operation.
Waterfall Pumps can process high volumes of water loaded with moderate amounts of solid particles, and are ideal for use with external filtration systems and for creating streams and waterfalls. Most modern Waterfall pumps are energy efficient, and have built in protective housings that prevent clogging, and keep larger damaging debris out of the pumps impeller.