This is a precise, fully isolated pH circuit constructed using high quality components and is designed to integrate with the Robo-Tank aquarium controller. Don't have or need the controller, that's OK, you can connect it directly to an Arduino, PI or any other microcontroller with I2C. The circuit comes with an easy to use open source library, you'll be measuring pH in no time.

The Robo-Tank line of circuits utilize the newest isolation technology (power and data) to prevent noise from entering the circuit through the microcontroller, power supply or your aquarium. A pH circuit is a delicate volt meter and it doesn't take much to cause interference, with full isolation noise is blocked so you continue to get accurate readings. This also blocks interference from multiple probes in the same aquarium.

The circuits communicate with the Arduino, PI or any other microcontroller using the popular I2C bus which allows you to connect multiple circuits using only 2 pins (SCL/SDA).

Circuits connect using a USB cable or header jumpers. There's an extra set of headers on PCB to daisy chain multiple circuits.

• Fully Isolated power and data lines
  
• Outputs pH, pOH, estimated CO2
• Temperature Compensation
• 1 and 2 Point Calibration Modes
• Auto Calibration Feature
• Plug and Play with any Arduino using the open source library and test sketch
• Manually Change and Save I2C Address to circuit
• Manually Change and Save kH value to estimate CO2
• Slope of Probe is calculated to monitor the health of your probe
• 0.001 - 14.000 Range
• 0.001 Resolution (thousands)
• +/- 0.002 Accuracy
• Read Every 1.8 Seconds
• Compatible with any brand and type of pH probe with BNC connector
• 3.3v - 5v Operating Range
• I2C Communication with Microcontroller
• 30mm x 70mm PCB size

Add an optional I2C buffer on right side of page, this will allow you to extend the cable between the circuit and controller up to 15 meters, for Robo-Tank users this is good for Gen1 and Gen2 hardware, not needed for Gen3. 

Add an optional USB expansion hub for more USB ports for Gen3 controller.

Add an optional 3D printed case for the circuit or hub, optionally you can print one yourself by downloading the STL files from your account.