Show HN: Open hardware for hydroponic automation (EC, pH, irrigation, etc.)

In hydroponic culture, it's typical to measure and continuously adjust the pH and fertilizer content of the solution, using electrical conductivity (EC) as a proxy for fertilizer content and a glass electrode for pH. This is open hardware to make those measurements and automatically drive the pumps that dose fertilizer or acid, interfacing via http over Wi-Fi. Such systems are widely used commercially, but too expensive for most small-scale or amateur use. I've seen various hobbyist systems assembled from dev boards, but it's neater and cheaper to have everything in a single PCBA.

Since these boards currently do everything I need for the plants on my balcony, I don't plan to develop the firmware much more myself. I believe there's lots of opportunity for that, though--to build a UI that's friendlier to nontechnical users, to interface with existing home automation or other front-end software, to apply to other domains (aquaria, reef tanks), etc. So I'm posting this here with the hope that someone might be interested to build and extend, and glad to answer any questions.