A water quality sensor is a type of device used to measure and monitor parameters of water quality. These sensors that can read the physical, chemical and biological attributes of water. Water quality sensors are indispensable for assessing the water resources, maintaining human health and protecting aquatic habitat.

pH:

A measure of the acidity or alkalinity of water, which is crucial for aquatic life and various industrial processes.

Dissolved Oxygen (DO): 

The amount of oxygen dissolved in water, which is vital for the survival of aquatic organisms.

Turbidity: 

A measure of the clarity of water, indicating the presence of suspended particles. High turbidity can be a sign of pollution or runoff.

Conductivity: 

A measure of the water's ability to conduct an electric current, which can indicate the presence of dissolved salts and minerals.

Temperature: 

Water temperature can affect the solubility of gases and the metabolic rates of aquatic organisms.

Total Dissolved Solids (TDS): 

The combined content of all inorganic and organic substances dissolved in water.

Biochemical Oxygen Demand (BOD): 

An indication of the amount of biodegradable organic matter in water, which can deplete oxygen levels.

Chemical Oxygen Demand (COD): 

A measure of the amount of organic matter that can be chemically oxidized in water.

Nitrate and Phosphate Levels: 

Important for assessing nutrient pollution, which can lead to eutrophication.

Bacteriological Quality: 

The presence of bacteria such as E. coli or coliforms, which can indicate fecal contamination and pose health risks.

Y505-A Dissolved Oxygen Sensor for Aquaculture 

1. Adopt fluorescence method

2. Digital sensor, supports RS485, MODBUS protocol

3. No oxygen consumption, no flow limit

If you have any inquiries, please don't hesitate to contact us. We are here to assist you with dedicated service.

Yosemitech optical dissolved oxygen probe provides high accuracy in measuring dissolved oxygen levels, making it an essential tool for aquaculture, environmental monitoring, and aquatic research. 

Why choose Yosemitech's Optical Do Sensor? 

Advanced Technology: High performance self-developed fluorescent material, no oxygen consumption, no flow limit, no electrolyte. 

User-friendly Design: Easy to install and operate, it’s perfect for both seasoned professionals and newcomers to the field. 

Durability: Adopting titanium housing. Suitable for withstand harsh environments. 

If you are finding a optical dissolved oxygen sensor, Yosemitech is your best choice!

Portable dissolved oxygen meter adopts fluorescence measurement principle. Key features of this device include the absence of oxygen consumption during measurement, no flow rate limitations, no need for preheating, no requirement for electrolyte.

From April 21th to 23rd, 2025, IE Expo China 2025 concluded successfully at the Shanghai New International Expo Centre. As a highly anticipated communication platform in the industry, the exhibition attracted exhibitors, experts, scholars, and industry elites from around the world to gather in Shanghai. Through various forms such as cutting - edge technology displays and high - end forum sharing, it created a professional and forward - looking audio - visual feast for the industry.

Suzhou Yosemite Technology Co., Ltd. ("YOSEMITECH"), which has been deeply involved in the water quality monitoring field for over 11 years, always adheres to the mission of "Water Monitoring Made Simple". YOSEMITECH showcased its self - developed water quality monitoring sensors and instruments at the exhibition. As a manufacturer of water quality monitoring sensors, we had in - depth exchanges with domestic and foreign partners and industry peers during the exhibition. It fully demonstrated its profound expertise in areas such as water quality sensor research and development and intelligent monitoring system integration, and continuously empowered global water quality monitoring scenarios with innovative technologies to promote the efficient and intelligent development of the industry.

Y532-A Digital pH Sensor Calibration

Required equipments and raw materials
Required equipments: four 1000mL beakers, one set of gloves.
Raw materials: three pH standard liquid powders and deionized water.

Calibration steps

There are three methods of user calibration for the pH sensor: 3-points calibration.
3-point calibration was done in 4.01、6.86、9.18 standard solution.

3-points calibration step

Connection method of connecting RS485 to USB connector: the red wire connects the positive terminal of the power supply, the black wire connects the negative terminal of the power supply, the green wire connects the A of the RS485 interface, the white wire connects the B of the RS485 interface, as shown in the following figure.

Y560-A Self-cleaning Ammonia Sensor Calibration

Required equipments and raw materials
Required equipments: three 1000mL beakers, one set of gloves.
Raw materials: 10mg/L ammonium ion electrode standard solution, 100mg/L ammonium ion electrode standard solution and deionized water.

Calibration steps
There are two methods of user calibration for the ammonium ion electrode of the ammonia nitrogen sensor: 1-point calibration and 2-points calibration.
1-point calibration was done in 10mg/L standard solution, 2-points calibration was done in 10mg/L standard solution and 100mg/L standard solution.

1-point calibration step (change the K value)

Step 1: put an appropriate amount of 10mg/L ammonium ion electrode standard solution into a 250mL beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution).
Step 2: connect the cable to the sensor, remove the sensor protective cover, remove the protective sleeves of the ammonium ion electrode, pH electrode and reference electrode, and then install the sensor protective cover. Put it into the  beaker containing 10mg/L ammonium ion electrode standard solution, and insert the RS485 to USB connector connected to the sensor cable into the computer.
Step 3: open the SmartPC software on the computer, then click “Calibrate”, and click “Get” under the “Manual Calibration” interface to get the initial K and B values of the sensor. Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 10, click “1 points” to do one-point calibration, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K value is written correctly.
Step 4: click “Start” under the “NH4-N” interface to get the real-time measurement of the pH、NH4+、NH4-N and temperature, check that the NH4+ is close to 10mg/L to verify that the one-point calibration is successful.

2-points calibration step (change the K and B values)

Step 1: put an appropriate amount of 10mg/L ammonium ion electrode standard solution into beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution). Put an appropriate amount of 100mg/L ammonium ion electrode standard solution into beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution).
Step 2: connect the cable to the sensor, remove the sensor protective cover, remove the protective sleeves of the ammonium ion electrode, pH electrode and reference electrode, and then install the sensor protective cover. Put it into the  beaker containing 10mg/L ammonium ion electrode standard solution, and insert the RS485 to USB connector connected to the sensor cable into the computer.
Step 3: open the SmartPC software on the computer. Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 10, change the “Second Point Calibration Value” to 100, click “2 points” to do two-points calibration, wait for the values in the pop-up window to stabilize, and click “OK”. Then clean the sensor with distilled water or deionized water, wipe it dry and put it into the beaker containing 100mg/L ammonium ion electrode standard solution, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K and B values are written correctly.
Step 4: click “Start” under the “NH4-N” interface to get the real-time measurement of the pH、NH4+、NH4-N and temperature, check that the NH4+ is close to 100mg/L, then clean the sensor with distilled water or deionized water, wipe it dry and put it into the beaker containing 10mg/L ammonium ion electrode standard solution, check that the NH4+ is close to 10mg/L to verify that the two-points calibration is successful.

Y561-A NH4-N Ammonia Sensor Calibration

Required equipments and raw materials
Required equipments: three 1000mL beakers, one set of gloves.
Raw materials: 10mg/L ammonium ion electrode standard solution, 100mg/L ammonium ion electrode standard solution and deionized water.

Calibration steps
There are two methods of user calibration for the ammonium ion electrode of the ammonia nitrogen sensor: 1-point calibration and 2-points calibration.
1-point calibration was done in 10mg/L standard solution, 2-points calibration was done in 10mg/L standard solution and 100mg/L standard solution.

1-point calibration step (change the K value)

Step 1: put an appropriate amount of 10mg/L ammonium ion electrode standard solution into a 250mL beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution).
Step 2: connect the cable to the sensor, remove the sensor protective cover, remove the protective sleeves of the ammonium ion electrode, pH electrode and reference electrode, and then install the sensor protective cover. Put it into the  beaker containing 10mg/L ammonium ion electrode standard solution, and insert the RS485 to USB connector connected to the sensor cable into the computer.
Step 3: open the SmartPC software on the computer, then click “Calibrate”, and click “Get” under the “Manual Calibration” interface to get the initial K and B values of the sensor. Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 10, click “1 points” to do one-point calibration, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K value is written correctly.
Step 4: click “Start” under the “NH4-N” interface to get the real-time measurement of the pH、NH4+、NH4-N and temperature, check that the NH4+ is close to 10mg/L to verify that the one-point calibration is successful.

2-points calibration step (change the K and B values)

Step 1: put an appropriate amount of 10mg/L ammonium ion electrode standard solution into beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution). Put an appropriate amount of 100mg/L ammonium ion electrode standard solution into beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution).
Step 2: connect the cable to the sensor, remove the sensor protective cover, remove the protective sleeves of the ammonium ion electrode, pH electrode and reference electrode, and then install the sensor protective cover. Put it into the  beaker containing 10mg/L ammonium ion electrode standard solution, and insert the RS485 to USB connector connected to the sensor cable into the computer.
Step 3: open the SmartPC software on the computer. Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 10, change the “Second Point Calibration Value” to 100, click “2 points” to do two-points calibration, wait for the values in the pop-up window to stabilize, and click “OK”. Then clean the sensor with distilled water or deionized water, wipe it dry and put it into the beaker containing 100mg/L ammonium ion electrode standard solution, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K and B values are written correctly.
Step 4: click “Start” under the “NH4-N” interface to get the real-time measurement of the pH、NH4+、NH4-N and temperature, check that the NH4+ is close to 100mg/L, then clean the sensor with distilled water or deionized water, wipe it dry and put it into the beaker containing 10mg/L ammonium ion electrode standard solution, check that the NH4+ is close to 10mg/L to verify that the two-points calibration is successful.

Yosemitech Y552-B UV254 COD Sensor Calibration

Required equipments and raw materials
required equipments: three 250ml brown bottles, one 1L brown bottles, one power adapter, one USB converter, 10m cable.
raw materials: 150mg/L standard solution, 450mg/L standard solution, distilled water or deionized water.

Calibration steps
There are two methods of user calibration for the COD sensor: 1-point calibration and 2-points calibration.
1-point calibration was done in 150mg/L standard solution, 2-points calibration was done in 150mg/L and 450mg/L standard solution.

1-point calibration step (change the K value)

Step 1：Put the COD sensor into deionised water. Open the SmartPC software and click "self-calibration". Wait for the self-calibration value to stabilize.

Step 2：Then put the COD sensor into 150mg/l standard solution, click "1 Point". Wait for the 1 point calibration value to stabilize.

2-points calibration step (change the K and B values)

Step 1：Put the COD sensor into deionised water. Open the SmartPC software and click "self-calibration". Wait for the self-calibration value to stabilize.

Step 2：Then put the COD sensor into 150mg/l standard solution, click "2 Point". Wait for the calibration value to stabilize in the first solution.

Step 3：Then put the COD sensor into 450mg/l standard solution, Wait for thecalibration value to stabilize in the second solution.

Y521-A Conductivity (salinity) sensor calibration

Required equipments and raw materials
Required equipments: two 250mL beakers, one set of gloves.
Raw materials: 1.4083mS/cm conductivity standard solution, 12.852mS/cm conductivity standard solution.

Calibration steps
There are two methods of user calibration for the conductivity sensor: 1-point calibration and 2-points calibration.
1-point calibration was done in 1.4083mS/cm conductivity standard solution, 2-points calibration was done in 1.4083mS/cm conductivity standard solution and 12.852mS/cm conductivity standard solution.

1-point calibration step (change the K value)

Step 1: put an appropriate amount of 1.4083mS/cm conductivity standard solution into a 250mL beaker, put the sensor into the beaker, shake the sensor gently to remove air bubbles from the front of the sensor;

Step 2: Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 1.4083, click “1 point” to do one-point calibration, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K value is written correctly;
Step 3: click “Start” under the “CT” interface to get the real-time measurement of the conductivity, TDS and temperature, check that the conductivity is close to 1.41mS/cm to verify that the one-point calibration is successful.

2-points calibration step (change the K and B values)

Step 1: put an appropriate amount of 1.4083mS/cm conductivity standard solution into a 250mL beaker, put an appropriate amount of 12.852mS/cm conductivity standard solution into another 250mL beaker;
Step 2: put the sensor into the beaker containing 1.4083mS/cm conductivity standard solution, shake the sensor gently to remove air bubbles from the front of the sensor;
Step 3: Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 1.4083, change the “Second Point Calibration Value” to 12.852, click “2 points” to do two-points calibration, wait for the values in the pop-up window to stabilize, and click “OK”. Then clean the sensor with distilled water or deionized water, wipe it dry and put it into the beaker containing 12.852mS/cm conductivity standard solution, shake the sensor gently to remove air bubbles from the front of the sensor, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K and B values are written correctly;
Step 4: click “Start” under the “CT” interface to get the real-time measurement of the conductivity, TDS and temperature, check that the conductivity is close to 12.85mS/cm, then clean the sensor with distilled water or deionized water, wipe it dry and put it into the beaker containing 1.4083mS/cm conductivity standard solution, shake the sensor gently to remove air bubbles from the front of the sensor, get the real-time measurement of the conductivity, TDS and temperature, check that the conductivity is close to 1.41mS/cm to verify that the two-points calibration is successful.

Y505-A Dissolved Oxygen Sensor Calibration

Required equipments and raw materials
Required equipments: two 1L beakers, one glass stirring bar, one air aeration pump, one set of gloves.
Raw materials: anhydrous sodium sulfite (CAS:7757-83-7), distilled water or deionized water.

Calibration steps
There are two methods of user calibration for the DO sensor: one-point calibration and two-points calibration.

One-point calibration step (change the K value)

Step 1: put an appropriate amount of distilled water or deionized water into a 1L beaker, turn on the air aeration pump and adjust to the maximum gear, introduce air into the water, about 30 minutes, the 100% oxygen water is prepared;

Step 2: connect the cable to the sensor, remove the rubber protective cap on the front end of the sensor and the sponge in the cap, install a black protective cover, put it into the 100% oxygen water, and insert the RS485 to USB connector connected to the sensor cable into the computer;

Step 3: open the SmartPC software on the computer, click “Language” and select “Chinese”, drop down “Port” and select the corresponding COM port, and then click “Connect”, after connecting the sensor successfully, click “Measure”. According to the actual situation (the default salinity is 0ppt, air pressure is 101.35KPa), modify the values of “Salinity” and “Air Pressure” through the “Get” and “Set” options, and then click “Start” to get the real-time measurement of the percentage of DO, DO and temperature;

Step 4: click “Stop” to end the data measuring, then click “Calibrate”, and click “Get” under the “Manual Calibration” interface to get the initial K and B values of the sensor. Click “Restore” under the “Automatic Calibration” interface, select “OK” in the pop-up window, and then click “Get” to check whether the K and B values are restored to the default values (the default K value is 1, and the default B value is 0).

Step 5: under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 100, click “1 point” to do one-point calibration, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K value is written correctly;

Step 6: click “Start” under the “DO” interface to get the real-time measurement of the percentage of DO, DO and temperature, check that the percentage of DO is close to 100% to verify that the one-point calibration is successful.

Two-points calibration step (change the K and B values)

Step 1: put an appropriate amount of distilled water or deionized water into a 1L beaker, turn on the air aeration pump and adjust to the maximum gear, introduce air into the water, about 30 minutes, the 100% oxygen water is prepared. Put an appropriate amount of distilled water or deionized water into another 1L beaker, stir while adding anhydrous sodium sulfite, until anhydrous sodium sulfite is insoluble and solid crystal is appeared, the 0% oxygen water is prepared;

Step 2: connect the cable to the sensor, remove the rubber protective cap on the front end of the sensor and the sponge in the cap, install a black protective cover, put it into the 100% oxygen water, and insert the RS485 to USB connector connected to the sensor cable into the computer;

Step 3: open the SmartPC software on the computer, click “Language” and select “Chinese”, drop down “Port” and select the corresponding COM port, and then click “Connect”, after connecting the sensor successfully, click “Measure”. According to the actual situation (the default salinity is 0ppt, air pressure is 101.35KPa), modify the values of “Salinity” and “Air Pressure” through the “Get” and “Set” options, and then click “Start” to get the real-time measurement of the percentage of DO, DO and temperature;

Step 4: click “Stop” to end the data measuring, then click “Calibrate”, and click “Get” under the “Manual Calibration” interface to get the initial K and B values of the sensor. Click “Restore” under the “Automatic Calibration” interface, select “OK” in the pop-up window, and then click “Get” to check whether the K and B values are restored to the default values (the default K value is 1, and the default B value is 0).

Step 5: under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 100, change the “Second Point Calibration Value” to 0, click “2 points” to do two-points calibration, wait for the values in the pop-up window to stabilize, and click “OK”. Then put the DO sensor into the 0% oxygen water, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K and B values are written correctly;

Step 6: click “Start” under the “DO” interface to get the real-time measurement of the percentage of DO, DO and temperature, check that the percentage of DO is close to 0%, then put the DO sensor into the 100% oxygen water to get the real-time measurement of the percentage of DO, DO and temperature, check that the percentage of DO is close to 100% to verify that the two-points calibration is successful.

YOSEMITECH Y511-A Turbidity Sensor Calibration

Required equipments and raw materials
required equipments: three 1L brown bottles, one magnetic stirrer, one iron stand, two magnetic rotors, one set of gloves.
raw materials: 460NTU turbidity standard solution, distilled water or deionized water.

Calibration steps
There are three methods of user calibration for the turbidity sensor: 0-point calibration, 1-point calibration and 2-points calibration.
0-point calibration was done in deionized water, 1-point calibration was done in 460 NTU standard solution, 2-points calibration was done in deionized water and 460 NTU standard solution.

0-point calibration step (change the B value)

Put an appropriate amount of distilled water or deionized water into a 1L brown bottle, put the sensor in the center of the brown bottle, which not close to the wall around the brown bottle, and then fix the sensor with an iron stand, adjust the high and low position of the sensor. Pay attention to maintain a distance greater than 10cm between the front end of the sensor and the bottom of the brown bottle.
Under the “Automatic Calibration” interface, click “0 point” to do zero-point calibration, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the B value is written correctly.
Click “Start” under the “TUR” interface to get the real-time measurement of the turbidity and temperature, check that the turbidity is close to 0NTU to verify that the zero-point calibration is successful.

1-point calibration step (change the K value)
Put an appropriate amount of 460NTU turbidity standard solution into a 1L brown bottle, put in a magnetic rotor, place the brown bottle on the magnetic stirrer, and open the magnetic stirrer to stir the standard solution thoroughly. Put the sensor in the center of the brown bottle, which not close to the wall around the brown bottle, and then fix the sensor with an iron stand, adjust the high and low position of the sensor. Pay attention to maintain a distance greater than 10cm between the front end of the sensor and the bottom of the brown bottle.
Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 460, click “1 point” to do one-point calibration, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K value is written correctly.
Click “Start” under the “TUR” interface to get the real-time measurement of the turbidity and temperature, check that the turbidity is close to 460NTU to verify that the one-point calibration is successful.

2-points calibration step (change the K and B values)

Drop down “Port” and select the corresponding COM port, and then click “Connect”, after connecting the sensor successfully, click “Measure”. Under the “TUR” interface, click “Brush”, and click “Turn On Brush” under the “Wiper” interface to remove the bubbles on the test window. Click “Start” to get the real-time measurement of the turbidity and temperature.
Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 0, change the “Second Point Calibration Value” to 460, click “2 points” to do two-points calibration, wait for the values in the pop-up window to stabilize, and click “OK”. Then clean the sensor with distilled water or deionized water, wipe it dry and put it into the 460NTU turbidity standard solution after full stirring according to the method of step 2, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K and B values are written correctly.
Click “Start” under the “TUR” interface to get the real-time measurement of the turbidity and temperature, check that the turbidity is close to 460NTU, then clean the sensor with distilled water or deionized water, wipe it dry and put it into the 0NTU turbidity standard solution after full stirring according to the method of step 2 to get the real-time measurement of the turbidity and temperature, check that the turbidity is close to 0NTU to verify that the two-points calibration is successful.

Y560-A Self-cleaning Ammonia Sensor Calibration

Required equipments and raw materials
Required equipments: three 1000mL beakers, one set of gloves.
Raw materials: 10mg/L ammonium ion electrode standard solution, 100mg/L ammonium ion electrode standard solution and deionized water.

Calibration steps
There are two methods of user calibration for the ammonium ion electrode of the ammonia nitrogen sensor: 1-point calibration and 2-points calibration.
1-point calibration was done in 10mg/L standard solution, 2-points calibration was done in 10mg/L standard solution and 100mg/L standard solution.

1-point calibration step (change the K value)

Step 1: put an appropriate amount of 10mg/L ammonium ion electrode standard solution into a 250mL beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution).
Step 2: connect the cable to the sensor, remove the sensor protective cover, remove the protective sleeves of the ammonium ion electrode, pH electrode and reference electrode, and then install the sensor protective cover. Put it into the  beaker containing 10mg/L ammonium ion electrode standard solution, and insert the RS485 to USB connector connected to the sensor cable into the computer.
Step 3: open the SmartPC software on the computer, then click “Calibrate”, and click “Get” under the “Manual Calibration” interface to get the initial K and B values of the sensor. Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 10, click “1 points” to do one-point calibration, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K value is written correctly.
Step 4: click “Start” under the “NH4-N” interface to get the real-time measurement of the pH、NH4+、NH4-N and temperature, check that the NH4+ is close to 10mg/L to verify that the one-point calibration is successful.

2-points calibration step (change the K and B values)

Step 1: put an appropriate amount of 10mg/L ammonium ion electrode standard solution into beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution). Put an appropriate amount of 100mg/L ammonium ion electrode standard solution into beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution).
Step 2: connect the cable to the sensor, remove the sensor protective cover, remove the protective sleeves of the ammonium ion electrode, pH electrode and reference electrode, and then install the sensor protective cover. Put it into the  beaker containing 10mg/L ammonium ion electrode standard solution, and insert the RS485 to USB connector connected to the sensor cable into the computer.
Step 3: open the SmartPC software on the computer. Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 10, change the “Second Point Calibration Value” to 100, click “2 points” to do two-points calibration, wait for the values in the pop-up window to stabilize, and click “OK”. Then clean the sensor with distilled water or deionized water, wipe it dry and put it into the beaker containing 100mg/L ammonium ion electrode standard solution, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K and B values are written correctly.
Step 4: click “Start” under the “NH4-N” interface to get the real-time measurement of the pH、NH4+、NH4-N and temperature, check that the NH4+ is close to 100mg/L, then clean the sensor with distilled water or deionized water, wipe it dry and put it into the beaker containing 10mg/L ammonium ion electrode standard solution, check that the NH4+ is close to 10mg/L to verify that the two-points calibration is successful.

Y561-A NH4-N ammonia sensor calibration

Required equipments and raw materials
Required equipments: three 1000mL beakers, one set of gloves.
Raw materials: 10mg/L ammonium ion electrode standard solution, 100mg/L ammonium ion electrode standard solution and deionized water.

Calibration steps
There are two methods of user calibration for the ammonium ion electrode of the ammonia nitrogen sensor: 1-point calibration and 2-points calibration.
1-point calibration was done in 10mg/L standard solution, 2-points calibration was done in 10mg/L standard solution and 100mg/L standard solution.

1-point calibration step (change the K value)

Step 1: put an appropriate amount of 10mg/L ammonium ion electrode standard solution into a 250mL beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution).
Step 2: connect the cable to the sensor, remove the sensor protective cover, remove the protective sleeves of the ammonium ion electrode, pH electrode and reference electrode, and then install the sensor protective cover. Put it into the  beaker containing 10mg/L ammonium ion electrode standard solution, and insert the RS485 to USB connector connected to the sensor cable into the computer.
Step 3: open the SmartPC software on the computer, then click “Calibrate”, and click “Get” under the “Manual Calibration” interface to get the initial K and B values of the sensor. Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 10, click “1 points” to do one-point calibration, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K value is written correctly.
Step 4: click “Start” under the “NH4-N” interface to get the real-time measurement of the pH、NH4+、NH4-N and temperature, check that the NH4+ is close to 10mg/L to verify that the one-point calibration is successful.

2-points calibration step (change the K and B values)

Step 1: put an appropriate amount of 10mg/L ammonium ion electrode standard solution into beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution). Put an appropriate amount of 100mg/L ammonium ion electrode standard solution into beaker, add an ionic regulator solution in the corresponding proportion (2% of the total amount of solution).
Step 2: connect the cable to the sensor, remove the sensor protective cover, remove the protective sleeves of the ammonium ion electrode, pH electrode and reference electrode, and then install the sensor protective cover. Put it into the  beaker containing 10mg/L ammonium ion electrode standard solution, and insert the RS485 to USB connector connected to the sensor cable into the computer.
Step 3: open the SmartPC software on the computer. Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 10, change the “Second Point Calibration Value” to 100, click “2 points” to do two-points calibration, wait for the values in the pop-up window to stabilize, and click “OK”. Then clean the sensor with distilled water or deionized water, wipe it dry and put it into the beaker containing 100mg/L ammonium ion electrode standard solution, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K and B values are written correctly.
Step 4: click “Start” under the “NH4-N” interface to get the real-time measurement of the pH、NH4+、NH4-N and temperature, check that the NH4+ is close to 100mg/L, then clean the sensor with distilled water or deionized water, wipe it dry and put it into the beaker containing 10mg/L ammonium ion electrode standard solution, check that the NH4+ is close to 10mg/L to verify that the two-points calibration is successful.

Y514-A self-cleaning chlorophyll sensor calibration

Required equipments and raw materials
Required equipments: two 1L brown bottles, one iron stand, one set of gloves
Raw materials: 2mg/L chlorophyll standard solution and deionized water

Calibration steps
There are three methods of user calibration for the chlorophyll sensor: 0-point calibration, 1-point calibration and 2-points calibration.
0-point calibration was done in deionized water, 1-point calibration was done in 2mg/L chlorophyll standard solution, 2-points calibration was done in deionized water and 2mg/L chlorophyll standard solution.

0-point calibration step (change the B value)

Step 1: put an appropriate amount of distilled water or deionized water into a 1L brown bottle, remove the rubber protective cap on the front of the sensor and put the sensor in the center of the brown bottle, which not close to the wall around the brown bottle, and then fix the sensor with an iron stand, adjust the high and low position of the sensor. Pay attention to maintain a distance greater than 10cm between the front end of the sensor and the bottom of the brown bottle.
Step 2: Under the “Automatic Calibration” interface, click “0 point” to do zero-point calibration, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the B value is written correctly.
Step 3: click “Start” under the “CHL” interface to get the real-time measurement of the CHL and temperature, check that the CHL is close to 0 to verify that the zero-point calibration is successful.

1-point calibration step (change the K value)

Step 1: put an appropriate amount of 2mg/L chlorophyll standard solution into a 1L brown bottle, remove the rubber protective cap on the front of the sensor and put the sensor in the center of the brown bottle, which not close to the wall around the brown bottle, and then fix the sensor with an iron stand, adjust the high and low position of the sensor. Pay attention to maintain a distance greater than 10cm between the front end of the sensor and the bottom of the brown bottle.
Step 2: Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 227.1, click “1 point” to do one-point calibration, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K value is written correctly.
Step 3: click “Start” under the “CHL” interface to get the real-time measurement of the CHL and temperature, check that the CHL is close to 227.1 to verify that the one-point calibration is successful.

2-points calibration step (change the K and B values)

Step 1: put an appropriate amount of distilled water or deionized water into a 1L brown bottle, and put an appropriate amount of 2mg/L chlorophyll standard solution into another 1L brown bottle.
Step 2: remove the rubber protective cap on the front of the sensor, put the sensor in the center of the brown bottle containing distilled water or deionized water, which not close to the wall around the brown bottle, and then fix the sensor with an iron stand, adjust the high and low position of the sensor. Pay attention to maintain a distance greater than 10cm between the front end of the sensor and the bottom of the brown bottle.
Step 3: Under the “Automatic Calibration” interface, change the “Single/First Point Calibration Value” to 0, change the “Second Point Calibration Value” to 227.1, click “2 points” to do two-points calibration, wait for the values in the pop-up window to stabilize, and click “OK”. Then wipe the sensor dry and put it into 2mg/L chlorophyll standard solution according to the method of step 2, wait for the values in the pop-up window to stabilize, and click “OK” to complete the calibration. Click “Get” to check whether the K and B values are written correctly;
Step 4: click “Start” under the “CHL” interface to get the real-time measurement of the CHL and temperature, check that the CHL is close to 227.1, then clean the sensor with distilled water or deionized water, wipe it dry and put it into the distilled water or deionized water according to the method of step 2 to get the real-time measurement of the CHL and temperature, check that the CHL is close to 0 to verify that the two-points calibration is successful.