Ask the Plant Doctor! How to choose a suitable pump for hydroponics

Choose a pump according to the specific requirements of the hydroponic setup. Photo: 123rf.com

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Q Is it better to use an outdoor or submersible pump for hydroponics? – Kebun Crew

The choice of pump depends on the specific requirements of the hydroponic setup.

Submersible pumps operate underwater, are quieter, easier to install, and are suitable for lifting water over short distances.

However, owing to constant water exposure, they may have shorter lifespans. In addition, they are less powerful, making them unsuitable for larger systems. Outdoor pumps (inline or centrifugal) are more powerful, move water over greater distances, and are suitable for large-scale operations.

Positioned outside the water reservoir, they are less likely to corrode, but can be noisier and more difficult to install.

Submersible pumps are suitable for hobbyists or small-scale setups, whereas outdoor pumps are suitable for large-scale commercial operation.

In deep-water culture (DWC) systems, an air pump provides oxygen to the root zone, but nutrient circulation may not be necessary. In contrast, an ebb-and-flow system requires a pump to flood the growth bed with nutrients and then drain back into the reservoir.

Pump selection depends on the quantity of water to be circulated, head height (vertical distance from the surface of the nutrient solution to the tallest water dispensation point), and desired flow rate, typically indicated in gallons per hour (GPH) or litres per hour (LPH).

Consider an example: to circulate a 200-litre reservoir every two hours, a pump with a flow rate of 100 LPH is required. Let us also say the highest point at which water must be delivered is 1.5m above the level of the nutrient solution in the reservoir.

Pumps typically have a performance chart that indicates how the pump’s flow rate decreases with the height or head. In this example, the pump considered can move 200 LPH at a head height of 0.5m but might only move 100 LPH at a head height of 1.5m.

Therefore, to ensure a flow rate of 100 LPH at a head height of 1.5m, you need to choose a pump rated for a higher flow rate at a lower head height. Here, a pump rated at 400 LPH (0.5m) may be able to pump 100 LPH at a height of 1.5m, making it a suitable choice.

The specific performance of a pump can vary based on the model and manufacturer; therefore, these numbers are used for illustrative purposes.

Consult the pump’s performance chart and consider all factors when choosing a pump for a specific application. Note that any bends and curves in the tubing will reduce the flow rate and may warrant a more powerful pump.

Dr Christopher Teh heads the Dept of Land Management, Faculty of Agriculture, Universiti Putra Malaysia and coordinates the Healthy Garden series. The views expressed are entirely his own.