Orbit sells a set of catch cups:
…and has a easy-looking online calculator, where you pop in the data, and it tells you how long they recommend you run your sprinklers. It also does the math to tell you your uniformity.
Would this be a good idea for calibrating my Iro? I know I could do it cheaper with some cups and a ruler, but to be honest, I’d rather spend a few dollars and make the process easier and more accurate.
When I get the results, would I just adjust the running time for the zone in the Rachio app? (That sounds like the simple way to handle it.) Or would it be better to somehow use the data to figure out the average GPH of my sprinkler heads for that zone and set a custom head to that GPH? I don’t want to do something to mess up the plus/minus calculated adjustments that the Rachio app will apply to my system throughout the year.