An automatic control device for carbonate hardness in marine aquaculture

Abstract

This utility model relates to the field of marine aquaculture technology, and in particular to an automatic control device for carbonate hardness in marine aquaculture, comprising a reference liquid tank, a sampling and detection tube, a pH sensor, a sodium bicarbonate solution storage tank, a sampling pump, a reference liquid pump, an air pump, a sodium bicarbonate addition pump, a heater, a temperature sensor inside the detection tube, a temperature probe in the aquaculture tank, and a main controller, achieving low-cost, high-frequency detection of KH values, no waste liquid pollution, rapid response, and stable control.

Description

Technical Field

[0001] This utility model relates to the field of marine aquaculture technology, specifically to an automatic control device for carbonate hardness in marine aquaculture. Background Technology

[0002] In marine aquaculture, especially coral farming, seawater hardness (KH value) is a crucial water quality parameter. KH is defined as follows: 1 KH is equivalent to 10 mg / L of dissolved calcium bicarbonate in water. Its core function is to measure the concentration of carbonates and bicarbonates in the water, which effectively buffer the pH level and prevent drastic fluctuations. The relative stability of pH directly determines water quality stability, thus affecting the physiological state and healthy growth of corals. Generally, the ideal KH value for coral growth should be maintained between 7 and 12 dKH.

[0003] However, in actual aquaculture, as corals and other organisms continue their metabolic activities, bicarbonate ions in the water are constantly consumed, and acidic substances produced by biological metabolism gradually accumulate, causing the KH value of the water to gradually decrease or fluctuate. To maintain a stable KH value, traditional aquaculture methods require manual periodic measurement of the KH value and manual addition of sodium bicarbonate solution. This method is not only time-consuming and labor-intensive, but also makes it difficult to achieve high-frequency, accurate testing and timely adjustment, failing to meet the needs of refined marine aquaculture.

[0004] To overcome the limitations of manual operation, four types of automatic KH value detection devices have emerged in the existing technology. These devices all rely on a microcontroller-controlled peristaltic pump for quantitative sampling, and calculate the KH value through sensors and reagent titration, further calculating the amount of sodium bicarbonate to be added. However, each device has obvious drawbacks, as follows:

[0005] Hydrochloric acid pH testing equipment: This type of equipment uses dilute hydrochloric acid as a test reagent. It measures the pH value of the sample by adding dilute hydrochloric acid dropwise. When the pH value reaches a specific value, the KH value is calculated based on the amount of dilute hydrochloric acid already titrated. Its disadvantages are that the detection accuracy depends entirely on the accuracy of the pH probe, which ages over time and requires frequent calibration and annual replacement; otherwise, significant errors will occur, and the operation is cumbersome. Furthermore, if measurements are taken multiple times a day, the consumption of test reagent is extremely high, leading to increased operating costs. Additionally, the tested samples must be discarded directly, generating a large amount of waste liquid, which can alter the salinity of the water in the aquaculture tank, affecting water quality stability.

[0006] Optical sensor colorimetric equipment: This type of equipment uses the property that the reagent changes color with the concentration of KH by titrating a specific reagent, and the KH value is calculated by a optical sensor sensing the color change. Although it overcomes the shortcomings of the pH probe in the hydrochloric acid pH detection method, the color sensor itself has a large error and poor detection accuracy; it also suffers from the problems of "multiple measurements per day leading to high consumption of test reagents and high costs" and "discarding samples after testing generates waste liquid and affects the salinity of the aquaculture tank".

[0007] Mixed reagent colorimetric method equipment: This type of equipment simultaneously adds a mixture of dilute hydrochloric acid and a pH colorimetric reagent to the sample. When the color sensor detects a sudden change in sample color from blue to yellow or pink, the KH value is obtained by calculating the amount of reagent used. Although it improves upon some of the shortcomings of the first two types of equipment to a certain extent, it still does not solve the core problems of "high cost for high-frequency measurements" and "waste liquid affecting salinity".

[0008] Reference solution pH difference method device: This type of device is similar in principle to the present invention. It first takes a sample from the aquaculture tank and uses a test reagent to measure the KH value as a reference solution. Subsequent samplings compare the pH difference between the reference solution and the sample, and the KH value of the sample is calculated based on the ion balance equation. Its advantages include not using test reagents, enabling multiple online measurements per day, and the sample can be returned to the aquaculture tank without waste liquid generation. However, it has significant drawbacks: to ensure the reference solution and sample reach the same temperature and CO2 saturation, both require prolonged water bath and aeration treatment, resulting in at least a one-hour delay in obtaining test results after sampling, failing to reflect water quality status promptly; furthermore, the device requires four peristaltic pumps and two sampling tubes, leading to a complex structure and a significantly increased failure rate.

[0009] Based on the aforementioned shortcomings of existing technologies, there is an urgent need for an automatic control device for KH values ​​in marine aquaculture that can achieve "low cost, high precision, no waste liquid, fast response, and simple structure" to meet the actual needs of refined marine aquaculture. Utility Model Content

[0010] In view of the shortcomings of the existing technology, the purpose of this utility model is to solve the problems of high detection cost, waste liquid affecting water quality, long detection delay, complex structure and high failure rate, and to achieve low-cost, high-frequency detection of KH value, no waste liquid pollution, rapid response and stable control.

[0011] This utility model provides an automatic control device for carbonate hardness in marine aquaculture, including a reference liquid tank, a sampling and detection tube, a pH sensor, a sodium bicarbonate solution storage tank, a sampling pump, a reference liquid pump, an air pump, a sodium bicarbonate addition pump, a heater, a temperature sensor inside the detection tube, a temperature probe in the aquaculture tank, and a main controller.

[0012] The sampling and detection tube is placed inside the reference liquid tank, and the reference liquid tank can hold seawater taken from the marine organism breeding tank as a reference liquid.

[0013] The pH sensor is used to detect the pH value of the liquid in the sampling tube;

[0014] The sampling pump is a bidirectional peristaltic pump, with one end connected to the marine aquaculture tank and the other end connected to the sampling and testing tube. It is used to draw seawater from the aquaculture tank to the sampling and testing tube or to drain seawater from the sampling and testing tube back to the aquaculture tank.

[0015] The reference liquid pump is a bidirectional peristaltic pump, with its two ends connected to the reference liquid tank and the sampling and detection tube, respectively, and is used to draw the reference liquid in the reference liquid tank into the sampling and detection tube or to discharge the reference liquid in the sampling and detection tube back into the reference liquid tank.

[0016] The air pump is connected to the sampling and detection tube and is used to aerate the liquid in the sampling and detection tube.

[0017] The sodium bicarbonate addition pump is connected at one end to the sodium bicarbonate solution storage tank and at the other end to the marine organism aquaculture tank, and is used to add sodium bicarbonate solution into the aquaculture tank.

[0018] The heater is installed inside the reference liquid tank and is used to heat the reference liquid inside the reference liquid tank.

[0019] The temperature sensor inside the detection tube is installed on the sampling detection tube and is used to detect the temperature of the liquid inside the sampling detection tube.

[0020] The temperature probe in the aquaculture tank is used to detect the seawater temperature inside the marine organism aquaculture tank.

[0021] The main controller integrates a main control microcontroller, a Bluetooth / WIFI networking module, a touch LCD screen, and drive circuits for motors and heating devices. The main controller is electrically connected to a pH sensor, a sampling pump, a reference liquid pump, an air pump, a sodium bicarbonate dosing pump, a heater, a temperature sensor inside the detection tube, and a temperature probe in the breeding box. The touch LCD screen is used for local parameter setting and monitoring, and the Bluetooth / WIFI networking module is used for remote parameter setting and online data monitoring.

[0022] The main controller can control the heater to start or stop based on the temperature difference detected by the temperature sensor in the detection tube and the temperature probe in the aquaculture tank, so that the temperature of the reference liquid in the reference liquid tank is consistent with the temperature of the seawater in the aquaculture tank. It can also calculate the carbonate hardness value of the seawater in the aquaculture tank based on the pH value of the reference liquid and the seawater in the aquaculture tank detected by the pH sensor, combined with the bicarbonate and hydrogen ion balance equation, and control the sodium bicarbonate addition pump to add sodium bicarbonate solution to the aquaculture tank based on the difference between the carbonate hardness value and the set target value.

[0023] Preferably, the main controller controls the reference liquid pump to draw 15ml of reference liquid from the reference liquid tank into the sampling and detection tube, and at the same time controls the air pump to aerate the sampling and detection tube until the pH value detected by the pH sensor no longer changes within 2 minutes. At this time, the main controller records the pH value as H1, and then controls the reference liquid pump to discharge the reference liquid in the sampling and detection tube back to the reference liquid tank.

[0024] Furthermore, the main controller controls the sampling pump to draw 15ml of seawater from the marine aquaculture tank into the sampling and testing tube, while simultaneously controlling the air pump to aerate the sampling and testing tube until the pH value detected by the pH sensor no longer changes within 2 minutes. At this point, the main controller records the pH value as H2, and then controls the sampling pump to discharge the seawater in the sampling and testing tube back into the aquaculture tank.

[0025] Furthermore, the feature is that when the main controller calculates the carbonate hardness value of the seawater in the aquaculture tank based on the balance equation of bicarbonate and hydrogen ions, the balance equation is [HCO3] - ]2=[HCO3 - ]1×[H + ]1 / [H + ]2, of which [HCO3 - [1] represents the molar concentration of bicarbonate ions in the reference solution. + ]1 represents the hydrogen ion concentration in the reference solution, [H + ]2 represents the hydrogen ion concentration in the seawater of the aquaculture tank, [HCO3] - ]2 represents the molar concentration of bicarbonate ions in the seawater of the aquaculture tank; and the main controller will [HCO3] - ]2 is converted to the mass concentration of calcium bicarbonate to obtain the carbonate hardness value of the seawater in the aquaculture tank.

[0026] Furthermore, the sampling pump and the reference liquid pump can act as closed valves when they stop working to prevent liquid backflow.

[0027] Furthermore, the initial KH value of the reference liquid in the reference liquid tank is obtained by measuring the KH value detection reagent and is pre-input into the main controller.

[0028] Furthermore, the main controller controls the start-up, stop, and operating parameters of the sampling pump, reference liquid pump, air pump, sodium bicarbonate addition pump, and heater respectively through the motor and heating device drive circuits.

[0029] Furthermore, the Bluetooth / WIFI networking module supports connection to external terminal devices via Bluetooth or the Internet, enabling remote parameter setting and online data monitoring.

[0030] Furthermore, the touch LCD screen can display parameters such as reference solution temperature, aquaculture tank seawater temperature, reference solution pH value, aquaculture tank seawater pH value, aquaculture tank seawater carbonate hardness value, and sodium bicarbonate solution addition amount.

[0031] Furthermore, the heater is a ceramic heater.

[0032] Compared with the closest existing technology, the present invention has the following beneficial effects:

[0033] Reduce operating costs and avoid water pollution: This device does not require any testing reagents. It calculates the KH value only by the pH difference between the reference solution and the sample, completely eliminating the problem of "high cost due to testing reagent consumption". At the same time, the sample (seawater in the aquaculture tank) can be completely discharged back into the aquaculture tank after testing, with no waste liquid generated and no change in the salinity of the water in the aquaculture tank, ensuring water quality stability.

[0034] Improved detection accuracy and simplified operation: This device only needs to detect the relative difference in pH between the reference solution and the sample through a pH sensor. It does not rely on the absolute accuracy of the pH probe. Therefore, the pH probe does not need to be calibrated frequently and only needs to be maintained periodically (e.g., every six months). The operation is simple. It also avoids the accuracy defects of color sensors and has higher detection accuracy.

[0035] Shorten detection delay and achieve rapid response: Through "real-time monitoring by dual temperature sensors + active temperature control by ceramic heater", the reference solution can be quickly made to match the temperature of the seawater in the aquaculture tank, without the need for a long water bath; at the same time, taking advantage of the fact that the seawater in the aquaculture tank is close to CO2 saturation, the sample can reach CO2 saturation within 2 minutes of aeration. A single test only takes 10-15 minutes from sampling to result, which is much faster than the 1-hour delay of existing technologies. It can reflect the water quality status in a timely manner and realize timely adjustment of KH value.

[0036] Simplified equipment structure and reduced failure rate: This device adopts a structure of "single sampling tube + 3 peristaltic pumps" (the sampling pump and reference liquid pump are bidirectional peristaltic pumps, and the sodium bicarbonate addition pump is a unidirectional peristaltic pump). Compared with the existing technology of "double sampling tube + 4 peristaltic pumps", the number of components is reduced, the structure is simpler, the failure rate is significantly reduced, and the equipment manufacturing cost is reduced.

[0037] Supports local and remote monitoring, enhancing ease of use: The device is equipped with a touch LCD screen, enabling local parameter settings and operational status monitoring; it also integrates a Bluetooth and WIFI networking module, supporting remote viewing of parameters and modification of settings, making it suitable for centralized management in large-scale farming scenarios and improving ease of use. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of an automatic control device for carbonate hardness in marine aquaculture provided by this utility model. Attached image description:

[0040] 1. Reference liquid tank; 2. Sampling and detection tube; 3. pH sensor; 4. Sodium bicarbonate solution storage tank; 5. Sampling pump; 6. Reference liquid pump; 7. Air pump; 8. Sodium bicarbonate addition pump; 9. Heater; 10. Temperature sensor inside the detection tube; 11. Temperature probe of the breeding box; 12. Main controller. Detailed Implementation

[0041] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0042] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0043] This utility model provides an automatic control device for carbonate hardness in marine aquaculture, such as... Figure 1 As shown, it includes a reference liquid tank 1, a sampling and detection tube 2, a pH sensor 3, a sodium bicarbonate solution storage tank 4, a sampling pump 5, a reference liquid pump 6, an air pump 7, a sodium bicarbonate addition pump 8, a heater 9, a temperature sensor inside the detection tube 10, a temperature probe in the breeding box 11, and a main controller 12.

[0044] The sampling and detection tube 2 is placed inside the reference liquid tank 1, and the reference liquid tank 1 can hold seawater taken from the marine organism aquaculture tank as a reference liquid.

[0045] The pH sensor 3 is used to detect the pH value of the liquid in the sampling tube 2;

[0046] The sampling pump 5 is a bidirectional peristaltic pump, one end of which is connected to the marine organism breeding tank and the other end is connected to the sampling and detection tube 2. It is used to draw seawater from the breeding tank to the sampling and detection tube 2 or to drain the seawater in the sampling and detection tube 2 back to the breeding tank.

[0047] The reference liquid pump 6 is a bidirectional peristaltic pump, with its two ends connected to the reference liquid tank 1 and the sampling and detection tube 2 respectively. It is used to draw the reference liquid in the reference liquid tank 1 to the sampling and detection tube 2 or to drain the reference liquid in the sampling and detection tube 2 back to the reference liquid tank 1.

[0048] The air pump 7 is connected to the sampling and detection tube 2 and is used to aerate the liquid in the sampling and detection tube 2.

[0049] The sodium bicarbonate addition pump 8 is connected at one end to the sodium bicarbonate solution storage tank 4 and at the other end to the marine organism aquaculture tank, and is used to add sodium bicarbonate solution into the aquaculture tank.

[0050] The heater 9 is disposed in the reference liquid tank 1 and is used to heat the reference liquid in the reference liquid tank 1.

[0051] The temperature sensor 10 inside the detection tube is installed on the sampling detection tube 2 and is used to detect the temperature of the liquid inside the sampling detection tube 2.

[0052] The temperature probe 11 in the aquaculture tank is used to detect the seawater temperature inside the marine organism aquaculture tank.

[0053] The main controller 12 integrates a main control microcontroller, a Bluetooth WIFI networking module, a touch LCD screen, and drive circuits for motors and heating devices. The main controller 12 is electrically connected to the pH sensor 3, sampling pump 5, reference liquid pump 6, air pump 7, sodium bicarbonate addition pump 8, heater 9, temperature sensor inside the detection tube 10, and temperature probe 11 of the breeding box. The touch LCD screen is used for local parameter setting and monitoring, and the Bluetooth WIFI networking module is used for remote parameter setting and online data monitoring.

[0054] The main controller 12 can control the heater 9 to start or stop based on the temperature difference detected by the temperature sensor 10 in the detection tube and the temperature probe 11 in the aquaculture tank, so that the temperature of the reference liquid in the reference liquid tank 1 is consistent with the temperature of the seawater in the aquaculture tank; it can also calculate the carbonate hardness value of the seawater in the aquaculture tank based on the pH value of the reference liquid and the seawater in the aquaculture tank detected by the pH sensor 3, combined with the balance equation of bicarbonate and hydrogen ions, and control the sodium bicarbonate addition pump 8 to add sodium bicarbonate solution to the aquaculture tank based on the difference between the carbonate hardness value and the set target value.

[0055] The main controller 12 controls the reference liquid pump 6 to draw 15ml of reference liquid from the reference liquid tank 1 into the sampling detection tube 2, and at the same time controls the air pump 7 to aerate the sampling detection tube 2 until the pH value detected by the pH sensor 3 no longer changes within 2 minutes. At this time, the main controller 12 records the pH value as H1, and then controls the reference liquid pump 6 to discharge the reference liquid in the sampling detection tube 2 back to the reference liquid tank 1.

[0056] The main controller 12 controls the sampling pump 5 to draw 15ml of seawater from the marine aquaculture tank into the sampling and detection tube 2, and at the same time controls the air pump 7 to aerate the sampling and detection tube 2 until the pH value detected by the pH sensor 3 no longer changes within 2 minutes. At this time, the main controller 12 records the pH value as H2, and then controls the sampling pump 5 to discharge the seawater in the sampling and detection tube 2 back into the aquaculture tank.

[0057] When the main controller 12 calculates the carbonate hardness value of the seawater in the aquaculture tank based on the balance equation of bicarbonate and hydrogen ions, the balance equation is [HCO3-]. - ]2=[HCO3 - ]1×[H + ]1 / [H + ]2, of which [HCO3 - [1] represents the molar concentration of bicarbonate ions in the reference solution. + ]1 represents the hydrogen ion concentration in the reference solution, [H + ]2 represents the hydrogen ion concentration in the seawater of the aquaculture tank, [HCO3] - ]2 represents the molar concentration of bicarbonate ions in the seawater of the aquaculture tank; and the main controller 12 will [HCO3] - ]2 is converted to the mass concentration of calcium bicarbonate to obtain the carbonate hardness value of the seawater in the aquaculture tank.

[0058] When the sampling pump 5 and the reference liquid pump 6 stop working, they can act as closed valves to prevent liquid backflow.

[0059] The initial KH value of the reference liquid in the reference liquid tank 1 is obtained by measuring the KH value detection reagent and is pre-input into the main controller 12.

[0060] The main controller 12 controls the start-up, stop, and operating parameters of the sampling pump 5, reference liquid pump 6, air pump 7, sodium bicarbonate addition pump 8, and heater 9 respectively through the motor and heating device drive circuit.

[0061] The Bluetooth / WIFI networking module supports connection to external terminal devices via Bluetooth or the Internet, enabling remote parameter setting and online data monitoring.

[0062] The touch LCD screen can display parameters such as reference solution temperature, aquaculture tank seawater temperature, reference solution pH value, aquaculture tank seawater pH value, aquaculture tank seawater carbonate hardness value, and sodium bicarbonate solution addition amount.

[0063] The heater 9 is a ceramic heater.

[0064] The above description details one embodiment of the present utility model, but it is merely a preferred embodiment and should not be construed as limiting the scope of the present utility model. All equivalent variations and improvements made within the scope of the present utility model application should still fall within the patent coverage of the present utility model.

Claims

1. An automatic control device for carbonate hardness in marine aquaculture, characterized in that, Includes a reference liquid tank (1), a sampling and detection tube (2), a pH sensor (3), a sodium bicarbonate solution storage tank (4), a sampling pump (5), a reference liquid pump (6), an air pump (7), a sodium bicarbonate addition pump (8), a heater (9), a temperature sensor inside the detection tube (10), a temperature probe in the breeding box (11), and a main controller (12). The sampling and detection tube (2) is placed inside the reference liquid tank (1), and the reference liquid tank (1) can hold seawater taken from the marine aquaculture tank as a reference liquid; The pH sensor (3) is used to detect the pH value of the liquid in the sampling tube (2); The sampling pump (5) is a bidirectional peristaltic pump. One end of it is connected to the marine aquaculture tank, and the other end is connected to the sampling and testing tube (2). It is used to draw seawater from the aquaculture tank to the sampling and testing tube (2) or to discharge seawater from the sampling and testing tube (2) back to the aquaculture tank. The reference liquid pump (6) is a bidirectional peristaltic pump, with its two ends connected to the reference liquid tank (1) and the sampling detection tube (2) respectively. It is used to draw the reference liquid in the reference liquid tank (1) to the sampling detection tube (2) or to discharge the reference liquid in the sampling detection tube (2) back to the reference liquid tank (1). The air pump (7) is connected to the sampling and detection tube (2) and is used to aerate the liquid in the sampling and detection tube (2); The sodium bicarbonate addition pump (8) is connected at one end to the sodium bicarbonate solution storage tank (4) and at the other end to the marine organism aquaculture tank, and is used to add sodium bicarbonate solution to the aquaculture tank. The heater (9) is disposed in the reference liquid tank (1) and is used to heat the reference liquid in the reference liquid tank (1); The temperature sensor (10) inside the detection tube is installed on the sampling detection tube (2) and is used to detect the temperature of the liquid inside the sampling detection tube (2); The temperature probe (11) of the aquaculture tank is used to detect the seawater temperature inside the marine organism aquaculture tank; The main controller (12) integrates a main control microcontroller, a Bluetooth WIFI networking module, a touch LCD screen, and drive circuits for motors and heating devices. The main controller (12) is electrically connected to the pH sensor (3), sampling pump (5), reference liquid pump (6), air pump (7), sodium bicarbonate addition pump (8), heater (9), temperature sensor inside detection tube (10), and temperature probe of breeding box (11). The touch LCD screen is used for local parameter setting and monitoring, and the Bluetooth WIFI networking module is used for remote parameter setting and online data monitoring. The main controller (12) can control the heater (9) to start or stop according to the temperature difference detected by the temperature sensor (10) in the detection tube and the temperature probe (11) in the breeding box, so that the temperature of the reference liquid in the reference liquid tank (1) is consistent with the temperature of the seawater in the breeding box; it can also calculate the carbonate hardness value of the seawater in the breeding box according to the pH value of the reference liquid and the seawater in the breeding box detected by the pH sensor (3) and the balance equation of bicarbonate and hydrogen ions, and control the sodium bicarbonate addition pump (8) to add sodium bicarbonate solution to the breeding box according to the difference between the carbonate hardness value and the set target value.

2. The automatic control device for carbonate hardness in seawater mariculture according to claim 1, characterized in that, The main controller (12) controls the reference liquid pump (6) to draw 15ml of reference liquid from the reference liquid tank (1) into the sampling detection tube (2), and at the same time controls the air pump (7) to aerate the sampling detection tube (2) until the pH value detected by the pH value sensor (3) no longer changes within 2 minutes. At this time, the main controller (12) records the pH value as H1, and then controls the reference liquid pump (6) to drain the reference liquid in the sampling detection tube (2) back into the reference liquid tank (1).

3. The automatic control device for carbonate hardness in seawater mariculture according to claim 1, characterized in that, The main controller (12) controls the sampling pump (5) to draw 15ml of seawater from the marine aquaculture tank into the sampling and detection tube (2), and at the same time controls the air pump (7) to aerate the sampling and detection tube (2) until the pH value detected by the pH sensor (3) no longer changes within 2 minutes. At this time, the main controller (12) records the pH value as H2, and then controls the sampling pump (5) to discharge the seawater in the sampling and detection tube (2) back into the aquaculture tank.

4. The automatic control device for carbonate hardness in seawater mariculture according to claim 1, characterized in that, When the main controller (12) calculates the carbonate hardness value of the seawater in the aquaculture tank according to the balance equation of bicarbonate and hydrogen ions, the balance equation is [HCO3⁻]2=[HCO3⁻]1×[H⁺]1 / [H⁺]2, where [HCO3⁻]1 is the molar concentration of bicarbonate ions in the reference solution, [H⁺]1 is the concentration of hydrogen ions in the reference solution, [H⁺]2 is the concentration of hydrogen ions in the seawater in the aquaculture tank, and [HCO3⁻]2 is the molar concentration of bicarbonate ions in the seawater in the aquaculture tank; and the main controller (12) converts [HCO3⁻]2 into a mass concentration in terms of calcium bicarbonate to obtain the carbonate hardness value of the seawater in the aquaculture tank.

5. The automatic control device for carbonate hardness in seawater mariculture according to claim 1, characterized in that, When the sampling pump (5) and the reference liquid pump (6) stop working, they can act as closed valves to prevent liquid backflow.

6. The automatic control device for carbonate hardness in seawater mariculture according to claim 1, characterized in that, The initial KH value of the reference liquid in the reference liquid tank (1) is obtained by measuring the KH value detection reagent and is pre-input into the main controller (12).

7. The automatic control device for carbonate hardness in seawater mariculture according to claim 1, characterized in that, The main controller (12) controls the start-up, stop and operating parameters of the sampling pump (5), reference liquid pump (6), air pump (7), sodium bicarbonate addition pump (8) and heater (9) respectively through the motor and heating device drive circuit.

8. The automatic control device for carbonate hardness in seawater mariculture according to claim 1, characterized in that, The Bluetooth / WIFI networking module supports connection to external terminal devices via Bluetooth or the Internet, enabling remote parameter setting and online data monitoring.

9. The automatic control device for carbonate hardness in seawater mariculture according to claim 1, characterized in that, The touchscreen LCD can display the reference solution temperature, the seawater temperature in the aquaculture tank, the reference solution pH value, the seawater pH value in the aquaculture tank, the carbonate hardness value of the seawater in the aquaculture tank, and the amount of sodium bicarbonate solution added.

10. The automatic control device for carbonate hardness in seawater mariculture according to claim 1, characterized in that, The heater (9) is a ceramic heater.

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