pH/pCO₂monitoring controlThe system consists of a DAQ-M control host, pH monitor, CO2 control valve, and CapCTRL control software, which are used to monitor and adjust the pH value of water and dissolve CO₂Or temperature, can monitor and control the pH value and dissolved CO2 concentration of up to 4 different water bodies (such as breathing chambers), widely used in seawater acidification, water chemistry, high carbonation effect of aquatic organisms, water environment control (such as water environment control in aquatic organism respiration or behavior measurement), etc. The CO2 control valve controls the injection of CO2 into the CO2 cylinder (into the water), and the dissolved CO2 in the water (CO2 partial pressure) is indirectly measured by a pH meter. The opening of the CO2 control valve is regulated by CapCTRL control software to control the pH/pCO2 of the water (see figure below). The relationship between pCO2 and pH value can be calibrated by injecting different concentrations of CO2 standard gas.

Upper left image: The DAQ-M host is connected to a computer, and is also connected to four control valves to control the opening of the valves. The computer is connected to four pH meters to monitor the pH/pCO2 of four different water bodies (with pH meter probes in the water)

Top right figure: One end of the CO2 control valve connected to DAQ-M is connected to the CO2 cylinder, and the other end is connected to the gas stone, which is in the water body

System composition:

1. DAQ-MThe host can choose to regulate the pH/pCO2 of 1-4 different water bodies according to experimental needs

2. PHMeasurement of water pH to indirectly determine PCO₂Each water body is equipped with a pH monitor and probe for its concentration

3. CO2Control valve and gas stone: used to control the injection of CO2, where the CO2 cylinder is self configured

4. Temperature control unit (optional): including water pump, stainless steel heat dissipation ring and pipeline

5. CapCTRLSoftware: Used for online monitoring of water pH/pCO2 values and displaying them in graphical form, as well as controlling and setting pH/pCO2 levels

6. user's manual

Technical indicators:

1. 4Channel relay control, 100-240VAC (50-60Hz), can monitor and control pH/pCO2 of up to 4 different water bodies (breathing chambers or gas water containers)

2. 8Input channel, 0-10V, 14 bit resolution, signal-to-noise ratio of 62dB

3. USB2.0Port (connected to computer)

4. pHThe monitor has built-in time control data acquisition, waterproof level IP67, backlit LCD display screen, and weighs about 400g

5. pHElectrode: Built in temperature sensor, optional electrode suitable for freshwater or seawater, operating temperature 0-60 degrees Celsius, electrode length (seawater) 170mm

Origin: Europe

Typical applications:

A. Esbaugh, R. Heuer, M. Grosell.Impacts of ocean acidification on respiratory exchange and acid-base balance in a marine teleost,Opsanus beta[J]. J. Comp. Physiol. B. doi: 10.1007/s 00360-012-0668-5