Evapotranspiration happens top down
No, crop ET happens from the soil that the roots can reach and which it is able to use. Most likely, there are more roots near the surface, but for all calculations (except run-off) the assumption is that it is both used and filled evenly.
(This really isn’t related to the issue I’m concerned about anyway, which is that high ET isn’t accounted/adjusted for.)
High ET is accounted for with frequency. You unfortunately have an upper limit on that frequency that creates the issue. I live in a climate where my lawn goes from daytime temps of ~40F to 120F throughout the year. Right now Flex is irrigating about every other day. Come December or January that dials back to once every 4-5 days.
And I think the reason why is obvious: Flex Daily ignores high ET, and can only handle ET under its calculated irrigation.
That’s sounds like all the math Rachio has put into it is rarely any good.
I did a quick experiment with a new zone and schedule (all defaults but with Clay soil): after one week, it ends with 6% balance. Change the schedule to 3x/week, and you’re at 0% on 3 separate days. Change to 1x/week, and it will still only schedule 0.45” on a single day.
It should be scheduling 1.8”, which is the ET for the week.
Martin
Or to put it another way, Rachio can only handle ET that is lower than its calculated Daily value. Yet, the Flex Daily allows you to restrict it to watering as little as once per week, and does not warn you, and it does not compensate for it.
ET doesn’t get much higher than 110-120F and 7% humidity. That’s what I live through every summer.
Not at all. There are so many irrigation systems, with an infinite variation in PR rates, how could you pick one default to cover them all? Likewise, there are infinite combinations of soils that have different AW values from one neighborhood to the other. Again, how do you pick one for a default and expect it to be optimal. Put them all together and you can end up with a mess. Flex daily requires an investment in really understanding your yard and it’s true requirements. If you don’t have the desire to go through that it’s understandable, but then run a fixed schedule. It’s likely the correct one for you given the watering restrictions that you have.
I don’t want to go down some negative spiral here so I’ll leave this as my last comment. My intent was just to try to help and provide some clarification on what I believe to be an amazingly adaptable system, when given the right input and absence of severe water restrictions.
So after some more experimenting, I can see better how Rachio is doing it (I think, wrongly):
I’m having the same issue where the ET is higher then Irrigation. I’m using flex daily with coarse sandy soil and rachio is watering every day in the heat of summer and it can’t keep up. I’ll have ET all the way up to .4 but the system will only put down .21 of water leaving me constantly under “0 balance”. (.07 AWC, 6in root, 50% AD) It appears to me the system ignores anything under the allowed depletion when it should be dynamically increasing watering based on the true depletion to keep you above the AD. My grass is stressed unless i put in a second schedule for a top off or increase the allowed depletion to force a increased irrigation time.
I’ve the same situation — so I have temporarily increased the root depth from 6 to 9” or to wherever it appears the duration seems adequate and also increased the crop ET. So that is longer watering and higher frequency watering. But don’t think of it as root depth during this period, just as a temporary summer adjustment. Increase the depth a few inches and you’ll get quite a bit more in duration. Soak and run might become important. It is awesome that Rachio has all these levers to respond to harsh weather. Would be annoying to do on another controller.
But it would be nice of Iro could account for that excessive ET by, say, adding another watering or adding duration automatically. But at least it is ridiculously easy to work around. Problem is that adds complexity and make it harder to predict what adjusting the crop ET will do. We already have tons of questions on what all those advanced settings mean. I’m one that supports Keep It Simple, Silly. I’m also a lumper for data nerds reading this.
My 2 cents are that IF all of your other settings are correct, these workarounds may not be as good as supplemental schedules later in the day. The limitation is that Rachio only decides to irrigate once per day, but your zones deplete in less than 24 hours. If you irrigate more deeply, the roots may not get to that water anyway. However, if you let it deplete for 12 hours, then fill it some more, more of that water will be in the root zone.
Again, my 2 cents…
I am convinced to try supplemental watering to replace my previous described method. Thank you!
I find the issue to be rachio does not factor the water capacity below the allowed depletion (correct me if im wrong). If my roots are 6in with .07 awc that gives me .42 total water for the roots. When i have depletion set to 50% the software puts down .21 Now if I dip below 50% (aka “0”) and have higher ET’s the system still only waters .21 and struggles to stay above 50% when in reality it could put down up to .42 to bring it back to 100%
Exactly— see my post #12. I really hope they address this.
Martin, you have to recreate schedule after changing zone’s depletion, or your Schedule RUNTIME wouldn’t change.
Hey Rachio, but it seems to be wise to allow Flex daily to run more than once per day or to allow multiple flex daily schedules. The schedule would basically check the zone depletion and weather before the start and decide to run or not to run. Of course that adds more complex scenarios, when two flex daily schedules overlap. But this is a smart controller, you should be able to tackle this.
No, I haven’t found that to be the case when using the iOS app. The changes are reflected once I refresh/reload the schedule. It is not necessary to recreate the schedule.
Wow how annoying! So if I want it to water more, do I increase or decrease the allowed depletion? I thought going from 50 to 40 would be better. Apparently the directions are not clear now. Yet another time all my stuff is dieing when the weather changes and the “smart” controller can’t do its job. Honestly I never had problems like this with my dumb controller. It was simple to program and then just adjust the budget for the weather.
If you want to increase the watering frequency the easiest thing to do is adjust crop coefficient 5-10% up. I wouldn’t change allowed depletion. I always recommend using flex daily on one or two zones, get it dialed in, then apply to others if it is working out for you.
Adjusting duration is just editing the zone duration in the schedule. Hope this helps.
Here is some more useful information.
Thanks I’ll try that. I’ve read the articles as well but couldn’t glean what the easist way was.
The nice thing is that you can adjust crop coefficient, navigate to the moisture graph, and see the future watering simulation for the next two weeks change before your eyes 
That’s cool! So you adjust allowed depletion or/and root depth to get more water/irrgation cycle.