It's just going to be a 7 day timer that operates a pump submerged in a reservoir. I setup the pump and hoses, then measure how long it takes to deliver a specific amount of water, so the timer might come on twice or three times a week for a minute or two. For multiple plants I added a manifold to tweak the flow rates so each plant got about the right amount of water for the duration the pump ran. Probably not needed if all the plants are the same size.
I had used it several times in the past with no issues, but last year the timer failed after it turned on, and emptied the entire reservoir into the tent, then burned up the pump. I was lucky it failed the day before I left, so I could make other arrangements. I'm still not 100% sure I didn't program the timer wrong. It started working properly after I reset it to factory settings and reprogrammed it. Then I started wondering if I hadn't previously set the turn off time to the following day so it would run for 24 hours and two minutes.
