What is Resistance in a Pond Pump?
Every pond pump has a theoretical capacity, but in practice, it pumps less water due to resistance. Resistance is caused by two factors: head height (height difference) and hose resistance (friction). The higher the total resistance, the more the pump capacity decreases.
By consciously limiting resistance, you can make the pump work more efficiently and reduce energy costs. The right hose and setup make a big difference in this.
Head Height: The Height Difference
Head height is the vertical distance between the water surface and the highest point to which the pump pumps the water (e.g., a filter or waterfall). This distance determines the pressure the pump must overcome.
Tip: If the pump is on the pond bottom, only count the distance from the water surface to the endpoint. You do not need to include the depth of the pump underwater.
A pump with a 3-meter head height can pump 3,000 liters per hour at 0 meters height, but only 1,500 liters per hour at 2 meters head height. Always check the pump curve in the specifications.
Hose Resistance: Friction in the Pipe
Water flowing through a hose experiences frictional resistance. The narrower the hose and the rougher the inside, the more resistance. Bends, couplings, and taps also significantly increase resistance.
Hose resistance is often converted to "extra head height". For example, a 10-meter long hose with bends can give 0.5 to 1 meter of extra resistance, depending on the diameter and smoothness.
Note: A hose that is too narrow can reduce the pump capacity by 30 to 50%, even without a height difference.
Correct Hose Choice for Minimal Resistance
Choose a hose diameter that matches the largest connection size of your pond pump. Never go narrower than the pump outlet. For regular ponds and short distances, normal spiral hose is usually sufficient. For longer distances, many bends, or heavier pumps, choose reinforced spiral hose with a smooth interior for optimal flow.
Want to know more about hose selection? Read our ultimate guide to pond hoses with all the details about size and type.
Common Mistakes
- Using a hose that is too narrow: Drastically reduces capacity and makes the pump work harder.
- Placing too many bends: Every 90-degree bend adds extra resistance. Avoid sharp corners.
- Ignoring long horizontal distances: Horizontal pipes also provide resistance, especially at lengths above 10 meters.
- Stacking couplings: Each extra connection piece increases resistance. Use as few intermediate connections as possible.
Calculating Total Resistance
The total resistance is the sum of head height plus hose resistance. Example: 1.5 meters head height + 0.5 meters hose resistance = 2 meters total resistance. Find this point on the pump curve to see the actual capacity.
Tip: When choosing a pump, consider at least 1 meter of extra resistance for hose and couplings, even at short distances.
Related Solutions and Products
- View our full range of pond hoses for the right diameter and quality.
- Read the ultimate guide to pond hoses for detailed advice on hose selection.
- Consider a larger pump if you have a lot of head height or long pipes.