Selecting Pond Pumps

   Pond pumps are one of the most important factors for a healthy and properly functioning water feature. Pumps circulate the water creating sound and aeration while supplying dissolved oxygen crucial for living organisms and improved water quality. There are several sizes, types and brands of pumps on the market often causing confusion about which is the best choice for your water feature. To figure that which is the best pump for your situation, let’s first determine these following 6 factors. 

1. Pump Function- What do you need the pump to do? Start off by determining what you need the pump to do - run through a filter, add aeration in stagnant areas, run a waterfall or recirculate water. If you have multiple requirements for pumping and moving water you may use one larger pump to handle all your needs or have multiple smaller pumps for cost effectiveness or efficiency.  This can depend upon your budget, winterizing concerns and how the feature is constructed.

Smaller magnetic pump works well for "spitters"

2. Types of Pumps – Choosing the right pump(s) for the situation is determine by pump placement and motor type.  Pond pumps operate by placement in two main manners- either submersible or external (inline) with different types of motor options. Submersible pumps sit fully underwater inside of a skimmer, pump canyon or directly in the pond with some kind of intake protection. These pumps are ideal for most pond applications as they tend to be cost effective, operate quietly and run efficiently.

External or “inline” pumps sit outside the pond, in a dry, protected location- often inside a wooden or cement box with a lid for accessibility. External pumps tend to be better for moving large volumes of water, high head height water falls and ponds with bottom drains. They also tend to be noisier, less energy efficient, more complicated to install and maintain compared to submersible pumps. External pumps are designed to be either gravity fed (need to be located below the water level) or self-priming (can be above water level). Some submersible pumps can be run “inline”, where they sit outside of the pond drawing water directly “inline” with the plumbing. This set up is not as common usually intended for running filtration, stock tanks or other types of applications.  

Types of Pond Motor Options. There are many styles and  “series” of pumps by popular manufacturers like Aquascape, Atlantic, Danner (Pondmaster), Easy Pro, Little Giant, Performance Pro, PondMax, and Teton that typically are  branded by application.

-Magnetic Drive for Fountains, Bubblers & Small to Medium Ponds- this motor type uses magnets to drive the impeller for lower flow rates, lower head height and offers good energy efficiency.

- Asynchronous (Magnetic Direct Drive) for Small to Medium to Large Ponds with low head height- is a combination of magnetic drive efficiency with direct drive power.  

-Direct Drive for Solids Handling and High Head applications- the motor and impeller are directly connected, providing high power for waterfalls and larger ponds or lagoons.

3. Pond Volume. How much water volume do you have? Determine the gallons by calculation (see below) or using a water meter when filling the pond (or try the bucket method). You should recirculate the total pond volume every hour (with fish) or every 2 hours (without fish).

Irregular Shaped Ponds with Shelves: L (length-ft) x W (width-ft) x D (average depth-ft) x 7.48 x 0.8= Gallons

Irregular Shaped Ponds without Shelves: L (length-ft) x W (width-ft) x D (average depth-ft) x 7.48= Gallons

4. Determine Lift / Head Height. Elevation (in feet) how high will the pump need to go above the water surface. Pipe run and stream length causes friction loss, figure that

 Every 10’ pipe =1’ head height.    Maximum head height = no water flow or a trickle 

To determine head height: Elevation (in feet) + Pipe Length (in feet ÷ 10) = Appr. Head

 Bubbler Rocks/Pots and Fountains: this can get a little more tricky as you need to measure the vertical distance in feet per rock, distance pump submerged to the top of where the water comes out, the amount of pipe used (every 10’ of pipe =1’ of head height) and the friction loss from fittings and bends (90◦ elbows each is 1-2’ of head height). To determine the total head height, measure each rock in feet and combine them for total vertical lift: 

Total Head = Vertical Lift + (Pipe Length / 10) + Fitting Loss

Example for Total Vertical Lift - 3 Rock Bubbler measures, 3’ Rock, 2.5’ Rock and 2’ Rock in a basin 1.5’ deep (pump sits on the bottom). 3’ + 2.5’ + 2’= 7.5’

Flow Chart. Each model/series has a specific flow chart or pump performance chart that displays the lift or head height to help you determine which pump size is needed. Select a pump that is more 2-3 times higher than the head height on the flow chart.

Another general rule of thumb is to select a pump is to select a pump that is 2-3 times the volume of water. For example, if you have 500 gallons of water, select a pump that is around 1000-1500 gph.

Head height is the elevation or vertical height

5. Waterfall Width (if applicable). Measure the width of the waterfall to determine how much flow you are looking for. Waterfall Width (inches) x 125 Gallons = minimum flow rate. Every 125 gallons creates 1” of width

6. Match Pipe / Hose Type & Diameter with Type/Style of Pump. Once you have determined which type and size pump you are going to use, then you can choose which type of pipe or hose you can use.  Kink -free hose is easy, good for using barbed fittings, DIYer’s. Flexible PVC hose is more durable, needs to be glued into PVC fittings and there is a bit more installation techniques required, yet better quality than kink-free hose. The diameter of the hose determines how much water flows through it.

The perfect pump is energy efficient, runs the feature in a sustainable manner and should be easily accessible for maintenance, cleaning, and replacing when needed. This also goes hand in hand with choosing the appropriate plumbing to match your needs.

Pumps that are oversized or incorrect pump type installed:

Oversized or Undersized Pumps can fail prior to the warranty period. If this happens consistently, then chances are you may have the incorrect pump for your water feature.   Oversized pumps and especially direct drive pumps that need to pump in high head situations will fail if they are reduced too much with ball valves or restricted with a pipe size too small. Undersized pumps can fail from being overworked. What usually happens is they overheat and start shutting off or popping your breaker.

At Nature Perfect Pond & Supply Store our pond experts can help select the perfect pump and we can order a pump specific to your water feature from one of our suppliers if necessary.