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Discover the Nitto Kohki Linear Piston Air Pump Advantage

Discover the Nitto Kohki Linear Piston Air Pump Advantage

Posted by Dan on Aug 7th 2018

NITTO KOHKI always know as Medo pumps feature linear piston system proven in the aquaculture industries. NITTO KOHKI life expectancy of 6 years proper installation and maintenance of the pump.

NITTO KOHKI pumps feature a unique, patent-awarded linear-motor-driven free piston system that is globally proven in the wastewater treatment and aquaculture industries. This unique design theory eliminates the wear components typically found in conventional air compressors and vacuum pumps, such as crank shafts, connecting rods and ball bearings. The only moving part is the piston! Also eliminated is the need for any lubrication. Fewer parts translate into fewer problems.

A silicone diode between the coils converts the alternating current sine wave into a half-rectified input. The result is a pulsating electro-magnetic field energizing the resonant spring-mass (piston). When the electro-magnet is energized, the intake stroke of the piston compresses the return spring and draws air into the cylinder through the inlet valve in the head of the piston. When the electro-magnet is de-energized, the spring releases and the compression stroke of the piston forces the compressed air out of the cylinder through the reed style outlet valve.


  • Life expectancy of 6 years can be seen with proper installation and maintenance of the pump
  • Quiet operation allows the pump to run without disturbing the homeowner as can be the case with rotary vane units.
  • Designed to self-adjust should the pressure exceed the rated value of the pump, the piston stroke will automatically shorten to reduce the strain on the pump. At the same time, power consumption of the pump will decrease to protect against possible increasing temperatures.
  • Environmentally conscious design allows the pump to operate with lower energy consumption as it requres only 50-60% of the line currrent typically used by diaphragm pumps.
  • UL-listed for outdoor use

Discover the Nitto Kohki Linear Piston Air Pump Advantage


Several key points to consider when selecting an appropriate aerator for your koi pond are shown below.


The water depth at which the air is released into the pond will determine the primary operating back pressure of the pump. For every 1 foot of water depth, 0.43psi of resistance is encountered. The following chart provides the operating back pressure for the water depths indicated.


The overall water volume of the pond is a key factor in choosing an aerator. A rough estimate is that every 1000 gallons of water will need 40 liters of air per minute to sustain the appropriate dissolved oxygen level for koi. This is a general guideline. The number of koi and amount of vegetation in the pond also need to be taken into consideration. Please consult your koi provider for a more comprehensive oxygen requirement evaluation for your koi.

For rated pressures and airflows, please refer to the LA series data sheets for particular model information. It should be noted that a pump's maximum air flow and maximum operating pressure cannot be achieved simultaneously. As the pressure on the pump increases, the air flow will diminish. In turn, if the pressure on the pump decreases, its air flow will increase. This is true with all linear pumps.

Always install your pond aerator above the water level of the pond. This will prevent water from being siphoned back into the pump when it is turned off. It will protect you from the danger of water and electricity coming in contact with each other.