Hello, my name''s Jorge, I am an electronics engineer with experience writing firmware for embedded devices. I have three years of experience building custom systems using Raspberry Pis and Arduino boards.
I have read the details of your project, I am capable of completing the system as described. I'd like to know more details about the total system parts: the sensor to be used, the valves, and if there are any other constraints on the price or size of the parts to be used.
The raspberry pi is capable of using timers, based on the described behavior the raspberry clock can be used. If there is an additional requirement, we might need to add an additional board, without increasing too much the cost of the parts.
I already have several arduino boards, a couple of raspberry pis, and a raspberry touchscreen available, so we can start working as soon as we set up the requirements.
I'd be glad to discuss the project details with you, please write me back so we can talk about it, and start with your project as soon as possible.
Thanks in advance for your time.