Biological Factors

- Photosynthesis: Phytoplankton (e.g., algae) consume CO₂ during photosynthesis, reducing CO₂ levels and increasing pH. In summer, intense algal growth often raises water pH.

- Respiration: Aquatic organisms release CO₂ during respiration, lowering pH. At night, without photosynthesis, pH typically decreases.

- Organic Matter Decomposition: Microbial decomposition of organic matter (e.g., leftover feed, feces) produces organic acids, reducing pH. In aquaculture ponds, accumulated organic matter can significantly lower pH if oxygen is insufficient.

Chemical Factors

- Water Hardness: High water hardness limits pH increases due to calcium and magnesium ions forming precipitates with carbonate ions.  In low-hardness waters, pH rises more easily after CO₂ consumption by photosynthesis.

- Chemical Additives: Substances like quicklime increase pH, while acidic substances (e.g., organic acids, hydrochloric acid) decrease it.

Physical Factors

- Temperature: Rising temperatures reduce CO₂ solubility and increase photosynthesis rates, raising pH. However, temperature-induced water ionization slightly increases hydrogen ion concentration, with minimal effect on pH.

- Pressure: In high-pressure environments (e.g., deep sea), increased CO₂ dissociation lowers pH.

Other Factors

- External Water Sources: Introducing water with differing pH can drastically alter pond pH. For example, acidic or alkaline water sources significantly impact water body pH.

- Soil: Soil leachate affects pond pH. Acidic soils lower pH (e.g., southern mangrove areas), while coastal saline-alkaline soils raise it.

pH value, also referred to as the hydrogen ion activity index or acid-base indicator, quantifies the activity of hydrogen ions in a solution and serves as a standard for assessing the acidity or basicity of a solution under normal conditions. Typically, at standard temperature (approximately 25°C or 298 K), a pH value closer to 0 indicates a higher degree of acidity, while a pH value closer to 14 signifies a higher degree of alkalinity. A solution with a pH less than 7 is classified as acidic, whereas a pH greater than 7 denotes an alkaline solution. When the pH equals 7, the solution is considered neutral.

Oxidation-Reduction Potential (ORP) is defined as the difference between the redox potential of the indicator electrode and that of the reference electrode in a solution. It serves as a comprehensive metric reflecting the overall redox state of the system. ORP quantifies the macroscopic redox characteristics of all substances within the solution, specifically indicating the tendency for electron transfer. A positive ORP value signifies the oxidizing nature of the solution, whereas a negative ORP value denotes its reducing properties.

-pH Value

An increase in pH value typically results in a decrease in Oxidation-Reduction Potential (ORP), as oxidants tend to be more active in acidic environments.  

-Dissolved Oxygen (DO)

The concentration of dissolved oxygen (DO) is positively correlated with ORP and serves as a critical indicator of aerobic conditions. For instance, when DO levels in an aerobic tank exceed 2 mg/L, ORP values are relatively high. Conversely, under hypoxic conditions where DO is less than 0.5 mg/L, ORP decreases significantly.  

-Organic Substances and Reducing Agents

High concentrations of organic substances, such as chemical oxygen demand (COD), consume oxidants and thereby reduce ORP values. Reducing agents, including hydrogen sulfide and ammonia, directly weaken the oxidizing capacity, leading to a reduction in ORP.  

-Ion Interference

Heavy metal ions, such as iron (Fe²⁺), manganese, and copper, can alter ORP through redox reactions (e.g., Fe²⁺ oxidation reduces ORP). Cyanuric acid, a by-product of swimming pool disinfection, inhibits chlorine activity, resulting in lower ORP readings. Phosphate indirectly promotes algae growth, which can lead to a reduction in ORP values.  

Chlorophyll Sensors!

Ever wondered how we track algal blooms or monitor water health in real time? 

Dive into our latest video to explore Chlorophyll Sensors —  keeping our waters safe! 

What’s Inside?

 How to Use Yosemitech Self-cleaning Chlorophyll Sensor? 

Why Care? 

Chlorophyll sensors aren’t just gadgets — they’re guardians of freshwater and marine life.

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.

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.