Fish pond temperature monitoring device

Fish pond temperature monitoring device did you know that pond water temperature effects pond fish health? The fact is that temperature has big effects on the health of fish, and there are some things that to keep fish as healthy as possible, depending on what season it is.

Spring- the fluctuation in temperatures can be very stressful on fish. Add pond salt to help develop a healthy slime coat on your fish. This helps the fish naturally fend off any bacterial infections and parasites.

Summer- The perfect pond water should be in the range of 68 to 74 degrees Fahrenheit. Water loses much of its ability to hold oxygen when the temperature is above 85 degrees. Fish won’t be able to breathe.

Winter- Fish’s metabolism slows when your water cools down. They don’t need to eat when the temperature stays below 39 degrees Fahrenheit. An easy to digest food is suggested if the water is above 39 degrees. If you live in an area where water freezes, keep part of your pond open so that the toxic gases can be released.

Water temperatures shouldn’t change more than 5 degrees per day to keep your fish in their best health. To monitor the water, a good thermometer comes in handy. In the present project to monitor fish pond water temperature I would like to use “Maxim’s MAX31865 Evaluation Kit”. As of 2016, more than 50% of seafood was produced by aquaculture. So Maxim’s MAX31865 Evaluation Kit is more helpful to monitor the temperature of pond and take necessary steps in time to protect them from dying. This helps the fish farmers to make their pond suitable to their fish and can be beneficial to the produce food to the humans.

1) MAX 31865 Evaluation Kit and 2) RTD temperature Sensor.

The schematic diagram to record data from the sensor and convert it to digital data using on-board 16-bit ADC in max31865 chip.

Figure 1: Schematic diagram for RTD connected to MAX31865 chip.

Figure 2: Schematic diagram for SPI-to-USB converter circuit.

Procedure to install the GUI and connect Hardware:
The RTD sensor is connected to the MAX31865 Ev Kit, Follow the steps below to verify board operation:
1) Verify the two jumper wires (included) are properly secured in the terminal block in accordance with the 2-wire RTD Sensor Connector diagram on the PCB’s silkscreen.
2) Verify the 1kΩ resistor is properly secured in the terminal block connecting the RTDIN+ terminal to the RTDIN- terminal.
3) Set the EV kit hardware on a non-conductive surface that ensures that nothing on the PCB gets shorted to the workspace.
4) Prior to starting the GUI, connect the EV kit hardware to a PC using the supplied mini-USB cable, or equivalent. The POWER LED (D20) should be green and the COM LED (D21) should be red and slowly flash orange.
5) Windows should automatically begin installing the necessary device driver. The USB interface of the EV kit hardware is configured as a HID device and therefore does not require a unique/custom device driver. Once the driver installation is complete, a Windows message appears near the System Icon
menu indicating that the hardware is ready to use. Do not attempt to run the GUI prior to this message. If you try to run the GUI prior to this message, close the application and restart it once the driver installation is complete. On some versions of Windows, administrator privileges may be required to install the USB device.
6) Once the device driver installation is complete, visit to download the latest version of the EV kit software,
MAX31865EVKitSoftwareInstall.ZIP. Save the EV kit software to a temporary folder.
7) Open the .ZIP file and double click the .EXE file to run the installer. A message box stating “The publisher could not be verified. Are you sure you want to run this software?” may appear. If so, click Yes.
8) The installer GUI appears. Click Next and then Install. Once complete, click Close.
9) Go to Start >> All Programs. Look for the MAX31865EVKitSoftware folder and click on MAX31865EVKitSoftware.EXE inside the folder.
10) When the GUI appears, the text below the Maxim Integrated logo should indicate that the EV kit hardware is connected. The COM LED (D21) turns off and flashes red when communication occurs.

Figure: Software GUI of MAX31865 Ev Kit to start the temperature recording.

Source code

* MAX31865 Evaluation Kit program for fish pond temperature measurement.
#include <SPI.h>
#include <MAX31865.h>
#define RTD_CS_PIN 10
MAX31865_RTD rtd( MAX31865_RTD::RTD_PT100, RTD_CS_PIN );
void setup()
Serial.begin( 115200 );
/* Initialize SPI communication. */
SPI.begin( );
SPI.setClockDivider( SPI_CLOCK_DIV16 );
SPI.setDataMode( SPI_MODE3 );
/* Allow the MAX31865 to warm up. */
delay( 100 );
rtd.configure( true, true, false, true, MAX31865_FAULT_DETECTION_NONE,
true, true, 0x0000, 0x7fff );
void loop()
rtd.read_all( );
if( rtd.status( ) == 0 )
double temperature = rtd.temperature( );
Serial.print( " T = ");
Serial.print( temperature, 1 );
Serial.println(" deg C" );
Serial.print( "RTD fault register: " );
Serial.print( rtd.status( ) );
Serial.print( ": " );
if( rtd.status( ) & MAX31865_FAULT_HIGH_THRESHOLD )
Serial.println( "RTD high threshold exceeded" );
else if( rtd.status( ) & MAX31865_FAULT_LOW_THRESHOLD )
Serial.println( "RTD low threshold exceeded" );
else if( rtd.status( ) & MAX31865_FAULT_REFIN )
Serial.println( "REFIN- > 0.85 x V_BIAS" );
else if( rtd.status( ) & MAX31865_FAULT_REFIN_FORCE )
Serial.println( "REFIN- < 0.85 x V_BIAS, FORCE- open" );
else if( rtd.status( ) & MAX31865_FAULT_RTDIN_FORCE )
Serial.println( "RTDIN- < 0.85 x V_BIAS, FORCE- open" );
else if( rtd.status( ) & MAX31865_FAULT_VOLTAGE )
Serial.println( "Overvoltage or Undervoltage fault occured");
Serial.println( "Fault exist; Please check connection" );
delay( 3000 );
for more details on the source code visit the URL:

Instructions to monitor Fish pond data using MAX31865Ev Kit:

  1. Initially connect the 2-wire RTD sensor to the RTD port by replacing the 1kohm resistor in the Evaluation Kit.
  2. Plug in the USB cable to the PC and evaluation kit then open the GUI software which shows the EV kit is connected.
  3. ON the conversion mode, VBIAS, set to 2-wire RTD connection, if red bubble in fault status indicates their is open connection in the RTD sensor or in-appropriate sensor connected.
  4. If all is well then start to measure the data for the chosen environment.
  5. In our present project we are going to measure the fish pond water temperature. Water temperature is important to monitor and check whether the temperature is suitable for aquatic (fish) to survive in pond.
  6. We placed the RTD temperature Sensor in the pool to measure the temperature. The data recordings were saved in separate file to identify at what sun shine hour the temperature of the water is more.
  7. The data plotted on a graph gives an idea to the farmers to take necessary precaution to be followed to maintain the temperature within the limit to sustain the aquatic.
Temperature data in fish pond:

The details of taking observation in fish pond to record the temperature is shown in the video.

Improvement make this device more preferable
  1. Only single sensor can be connected to this if their is an option for multiple recordings it would me more advantages.
  2. If WiFi/ Bluetooth connectivity is available then it is easy for the user to utilize the kit for remote accessing the data from the measuring environment.
  3. An android app for smartphone will help to share the data and monitor in real-time.
In order to survive the fish in water they need an appropriate temperature based on the seasonal changes. MAX38165 evaluation kit helps the fish farmers to measure the temperature of water in-time and can take necessary action. The data can be saved in .CSV file which is more advantages to the ecologist to study on aquatic life. Once the fish sustain farmers will be the happiest person so that we to get food from them.
  • Like
Reactions: ram1234

Blog entry information

Last update

More entries in General

Share this entry