I just finished setting up my automatic watering system yesterday, and wanted to share it. I realized earlier this week that my plants would need to be watered while I was on spring break, and because it would be nearly impossible to find a way to get someone to water them for me, I figured I needed to setup an automatic watering system. I found a cheap 12v pump and vinyl tubing on amazon, and used a 10 gallon fish tank for a water reservoir. To control everything I am using a raspberry pi with a relay board. Currently, it just waters everything every two days, but eventually I plan on adding in water level sensors so the plants only get watered when they need to be. Though I am only using one pump, it is able to water multiple shelves using a method I found in a video posted by Meadoview where the water flows down to the next shelf when it reaches a certain level (the pictures below might demonstrate this better). This is only version 1.0, so any recommendations for future upgrades are welcome, and thanks for looking!
"water reservoir" and pump
Water comes into the top shelf via this tube
And when the water level gets above this tube, it drains to the next level
And enters the lower shelf here
Finally, any excess water drains back into the reservoir
The brains of the whole operation