A low-cost, accessible, and high-performing Arduino-based seawater pH control system for biological applications

• Main Author: Bockmon, Emily
• Format: Text
• Language: unknown
• Published: Open Science Framework 2021
• Subjects: Physical Sciences and Mathematics; Life Sciences; Ocean acidification
• Online Access: https://dx.doi.org/10.17605/osf.io/uzr7n; https://osf.io/uzr7n/

In the last two decades, the need for seawater pH control methodologies paralleled the rise in attention to the biological impacts of ocean acidification. Many effective and high-performing systems have been created, but they are often expensive, complex, and difficult to establish. We developed a system that is similarly high performing, but at a low cost and with a simple and accessible design. This system is controlled by an Arduino Nano, an open-source electronics platform, which regulates the flow of CO2 gas through electric solenoid valves. The Arduino and other inexpensive materials total ~$150 (plus CO2 gas and regulator), and a new treatment can be added for less than $35. Easy-to-learn code and simple wire-to-connect hardware make the design extremely accessible, requiring little time and expertise to establish. The system functions with a variety of pH probes and can be adapted to fit a variety of experimental designs and organisms. Using this set up, we were able to constrain seawater pH within a range of 0.07 pH units. Our system thus maintains the performance and adaptability of existing systems but expands their accessibility by reducing cost and complexity.