Dissolved oxygen (DO) is the amount of oxygen dissolved in water. It is a key parameter for biological treatment in sewage plants, water plant process control, aquaculture, environmental monitoring and industrial water quality management.

• Optical (fluorescence): the sensor cap is coated with a luminescent material. Blue light from an LED excites it, and it emits red light; the time and intensity of the red light depend on the oxygen concentration.
• Membrane (polarographic): oxygen diffuses through a membrane and is measured electrochemically.
• Electrochemical: an electrochemical sensor measures the oxygen reaction current.

Asmik optical sensors using fluorescence lifetime technology consume no oxygen, have no flow rate limitation, need no electrolyte, and are not affected by hydrogen sulfide, which makes them well suited to long-term online monitoring with low maintenance. Membrane (polarographic) sensors are a proven, cost-effective technology but require periodic membrane and electrolyte maintenance. Please send us your application details for a recommendation.

• MIK-DM2800: membrane (polarographic) dissolved oxygen meter with LCD display
• MIK-DO700: optical (fluorescence) dissolved oxygen meter
• MIK-DC2000: digital analyzer monitor for multiple water quality parameters, including DO
• MIK-DO7011: membrane dissolved oxygen sensor
• MIK-DO7012, MIK-DO7017, MIK-DO7018: optical dissolved oxygen sensors
• MIK-DO7019: fluorescent dissolved oxygen transmitter
• MIK-DO7013: electrochemical sensor for aquaculture, water quality testing and IoT monitoring

If you are unsure, send us your application details and our engineers will recommend a model.

The solubility of oxygen depends on water temperature, pressure and salinity. Asmik DO meters provide automatic temperature compensation; for saline water or high-altitude sites, please tell us the salinity and atmospheric pressure so they can be taken into account.

Dissolved oxygen is commonly expressed in mg/L (ppm) or as percent saturation (%). For example, the MIK-DC2000 covers a DO range of 0–40 mg/L. Please check each product page for its range.

Optical sensors greatly reduce maintenance compared with membrane sensors because they need no electrolyte or membrane replacement. Periodic cleaning of the sensor cap and checking the reading against a reference are still recommended, and the fluorescent cap is a wear part. Please follow the manual of your sensor.

Membrane sensors generally require periodic replacement of the membrane and electrolyte, cleaning, and recalibration. After installation or maintenance, the sensor typically needs a polarization period before stable readings are available.

Asmik fluorescent DO sensors, such as the MIK-DO7018 and MIK-DO7019, are designed to be free of hydrogen sulfide interference.

Membrane sensors consume oxygen during measurement and generally need a minimum water flow across the membrane for accurate readings. Asmik fluorescent sensors consume no oxygen and have no flow rate limitation.

Yes. Online DO monitoring in regulating pools, biochemical (aeration) tanks and effluent is a typical application. The MIK-DO7017 is widely used for these processes, and DO readings can be used to control blowers and save energy.

The MIK-DO7013 electrochemical sensor is widely used in aquaculture, water quality testing and IoT monitoring. Optical sensors are also suitable for long-term aquaculture monitoring with low maintenance.

Asmik DO sensors and transmitters offer good communication compatibility, including Modbus and standard signal outputs. Available outputs depend on the model; please check the product page or tell us your requirements.

• Immerse the sensor at a representative depth and location.
• Use a mounting bracket or pipe to keep the sensor stable.
• Avoid positions directly above aerators, where bubbles hit the sensor.
• Make sure the sensor can be removed easily for cleaning.
• For membrane sensors, ensure sufficient water movement across the membrane.

Please follow the installation manual of the selected model.

Typical industries include water and wastewater, environmental protection, aquaculture, food, pharmaceuticals, chemicals and power.

To help us select the correct model, please provide:

• Application (aeration tank, effluent, surface water, aquaculture, industrial water)
• DO range and water temperature
• Salinity and presence of hydrogen sulfide or oils
• Preferred technology (optical or membrane)
• Installation method and cable length
• Output requirements (Modbus, 4–20 mA) and power supply
• Whether a display controller is required
• Quantity

Send your requirements to info@asmik.com or contact us via WhatsApp at +86 13325716921.