Koi Pond Pump Selection Tips

The submersible pumps are the heart of the Koi pond.

Key specifications or rating for the pumps:

• Voltage = Voltage required in Volts (V).
• Current Drawn = Amount of current drawn, rated in Amperes (A)
• Power consumption = amount of power consumed rated in Watts (W)
• Flow Rate or maximum capacity = volume of water moved over time. Typically in cubic meters per min (m3/min) or litre per min.
• Maximum Head = maximum height of water that the pump can push water through. For example, the vertical height between the outlet of pump (e.g. top of waterfall) to the inlet to the pump (e.g. at the bottom of the pond or filter. The flow rate is inversely proportion to the head of water to be pushed.

The flow rate and number of pumps needed depends on many factors. There are many articles written on this subject and the rule of thumb is this: “Half the pond’s capacity (volume) needs to flow through the biological filter every hour”. So, do the calculations to determine the number of pumps and ratings of the pumps needed based on the capacity of the pond.

Depending on size of the pond, try to have a few small pumps than a single large one for redundancy in case one pump fail.  In addition, having a number of smaller pumps allows you to adjust the flow rate up or down by turning one or more pumps on or off. Connect them to separate power sources (with circuit breakers for safety) to create higher availability and redundancy.  As the electrical power cable for the pumps is usually about a few meters in length only, locate the power supply points as closed to the pump chamber of your filter as possible.

Have a spare pump in your house, especially if buying one requires a lead time longer than a few hours.

Other features to consider would be the auto cut-off when there is no water (useful for drain chamber).

For me, the pumps must be long lasting and be power efficient.   I am currently using 2 units of Tsurumi pumps (Model 40PU2.15S). They has been running almost non-stop for over 2 years now and consume a relatively low power of 150W each. In addition, I have another pump with auto-cutoff feature in my drain chamber; the drain pump is only used during pond maintenance.

When installing the pumps, devise a way for them to be removed without having to drain the pond or filter. Have a pipe coupling that allows the pump and attached outlet pipe to be decoupled at the top of the pond or filter. The whole pump, with the attached outlet pipe can then be lifted out for replacement.