I have been using Intermatic 48 pin 24 hour timer which is a 30 minutes on 30 minutes off timer (cost about $10.00) at Home Depot. Some times I can find 15 minutes on & off which is better for small gardens like the 11 plant because it doesn't take much time to fill a small garden. That is what the overflow pipe is for. So the
pump can flow until the timer shuts off even though it doesn't need to run for a half hour.