Smart Cycle Question

I have the smart cycle and water budgeting turned on, username canons900.

How can I tell if they are working. I did get a seasonal adjustment that increased my watering time. But how do I know if the water budgeting and smart cycle are working properly? Could this be a nozzle selection in my settings. I have different types of nozzles, i’ll call them rotating (moves left or right or in a 360) and fixed (simple pop up which sprays in a specified direction)? Does this make sense?

I do not have any bubblers or anything like that configured.

What would be really cool is if you guys developed your own set of sprinkler heads that could measure the amount of water, flow type of directional spray and have them communicate with the Iro for additional watering information and ways to program these heads to set a directional spray based on the head type, distance based on square footage or maybe the distances in a zone between the heads. And have the heads adjsut flow rate or distance as needed.

@canons900 Smart cycle will break-up your duration into multiple watering times, based on the maximum recommended run time of your nozzle, soil type, and slope.

This article has a matrix showing exactly how long we will run based on the characteristics defined above:

The surest way to see that we have indeed split up your schedule is to look at the zoom view on your calendar.

I have one zone that runs for 11 minutes, with cycle/soak it runs for 41 minutes. (5 minutes 30 seconds, 30 minute soak, 5 minutes 30 seconds). This can be viewed on the calendar:

If you are getting weekly seasonal adjustment emails, then water budgeting is enabled.

Our 2.0 software coming out soon, will have the concept of flex schedules, which will be a more efficient way to water budget.

Thanks and have a great day!


okay but i ma not seeing the same things in my calendar view. I have created 4 watering times starting at 2 am and I am still not seeing what you are seeing in the calendar view on the phone.

beginning to feel not so smart right now… and a little frustrated…

@canons900 If you send an email to they can review your schedule(s) and make sure they are setup correctly.

This matrix shows how we break up schedules based on your zone attributes:

Make sure there are no bubbler, emitter, or mister nozzles in schedules, since these will disable smart cycle.

I’m sure it’s something simple that support can help you determine if smart cycle is setup correctly.

:beers: helped me out last. Very quick response!!!

Can you post the solution? It will help other ppl having the same problem

The reply from @rachiosupport:

“Your smart cycle is actually working, your watering times for each zone simply aren’t breaching the maximum runtime threshold to be split up into multiple cycles. See this article for details: Smart Cycle Overview”

Here’s the article for anyone interested:

Smart Cycle Overview

Hope this helps!

If you use the following formula: Rt (max) = 60 (ASA)/(PR – IR), minutes (From: What Is Smart Cycle), what does it mean if your Precip rate is less than your Intake Rate and your answer is a negative value? Or what if your Precip Rate is equal to the Soil Intake Rate, then you would be dividing by zero.
How does the Iro deal with this?

I believe in this case the number of smart cycles would be zero, so essentially your duration would run as normal with no cycle/soak.


Ok. Understand, Im just trying to get through the math.

Therefore,if I were to add and MP Rotator as a nozzle and the have a PR of 0.39 in/hr and the DU is 80% I would have a PR(net) of 0.32 in/hr. If loam has a intake rate of 0.35 in/hr with no slope I would never be able to pool water.

That said in my loam soil I have an established mix shrub with 24" of of root depth. Deep roots equals greater storage and therefore longer gaps between watering days. So if I calculate it out I get watering every 15 days for 383 minutes. No cycles as the max run times is a negative number and therefore infinite. Is this possible or are there other limits to the Iro like must water within 14 days. Or is my math completely out the window?

@derek_USSI, just curious, are you setting up the MP Rotator as a rotary nozzle for the shrub zone? Or as a drip nozzle?

Is your goal to activate Smart Cycle for this zone? Let us know what your end goal on the math is and we can help you work back to it. :slight_smile:

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Hi Emil.
My end goal is to understand how the Iro makes decisions so that I can better inform our clients why it makes the decisions it does. I don’t own one myself, but the information that is given out seems to come from the Irrigation Association Auditor Handbook, literature.

So I’ve created an Excel Spreadsheet that I am trying to load with the information given from your articles and support.

But the problem I am having, as some of the info is slightly different from that of the IIABC here in BC (Canada). For example, the formula Rt (max) = 60 (ASA)/(PR – IR), minutes (From: What Is Smart Cycle). I’m wondering how the Iro, if using this formula, would deal with a PR that was less that the IR, as this would give a negative value. And in my above example, if there is no limit to Run time due to run off then the Iro could run every two week but for 6 hours for one zone.
This all said, I repeat, I do not own one, but I do have a customer who, like me, wonders why it makes the decisions it does.

Just figuring it all out.

Just to add, if the Iro uses Rt (max) = 60 (ASA)/(PR – IR), minutes as is stated in “What Is Smart Cycle” then the attached graph shows potential run times which grow exponentially large as the PR and IR become closer together. The second graphed data is the formula CRT = 60 x (IR/PR).

@derek_USSI, great! Happy to help explain the logic.

Any chance you could email me the spreadsheet you’ve created to review in more detail? My email is

In this situation, Smart Cycle would not be triggered as the soil would be able to absorb the water before any runoff can occur.

No, watering times are maxed at 3 hours and pending the type of schedule you setup. Fixed schedules will water on a static, defined schedule (day/interval); adjusting watering durations using statistical data and skipping schedules based on weather forecasts. Flex Schedules waters only when needed; dynamically adjusting watering days based on soil moisture needs.

In theory this makes sense as this is the calculation for max runtime. When PR = IR, the watering duration will be at it’s max.

I’m hoping this helps. Happy to review your spreadsheet if you’d like to send me a copy (or share via Google drive).

Best, Emil

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I’m pretty sure the documentation is wrong. It makes no sense to subtract ir from pr. We need a ratio here not a difference. So I’m going to assume that we should be dividing not subtracting.

As both values become closer to each other, then you produce a ratio closer to 1, so when they are the same, this division becomes idempotent, if you will.

So as The denominator approaches 1 the iro is allowed to apply water up to the asa as this formula indicates that no runoff is occurring as your absorption rate and your application rate are in sync, there is a minimum 30 minute soak period once asa is achieved (since asa will almost always be less than the application amount).

So going with hard numbers (but simple), to explain my reasoning, but I’m probably wrong. if you are somehow capable of putting together an irrigation system that can only apply .1 inch an hour, and you have your soil set to clay so your asa is set to .2, I would expect the iro to take 2 hours to apply water and a third hour for the asa to reduce to zero (because the second hour’s worth of water needs another hour to absorb) for your system to deliver .2 inches of water (see footnote 1). If the moisture level is being raised to 1 inch, you can see how you are going to,run away on time and require 14 hours (last hour gets an implied soak as the schedule is complete). Now, to really put anybody reading to sleep, if we doubled our pr to .2, then we get a ratio that equals 2, .2 / .1 = 2 as we would expect, because we have doubled our application rate so we should achieve asa in half the time, 1 hour, then 1 hour to soak, bringing our total time down to 9 hours.

But you can’t remove the asa as you have in the second graph as this value is directly inproportionate with slope, as slope increases Asa decreases and you run the risk of loosing water due to run off, especially as pr goes up. Thus you are only computing how much time the irrigation should run to put out all water, ignoring how much actually translocated into the ground.

Either way, we are all about to learn something. we will wait for the Emil or the franz to chime in, however, I would expect this curve to appear asymptotic (as pr goes up) as demonstrated by your graphs, so i think your data tables are generated correctly, just with an inaccurate denominator.

Edit: I’ll dig into your spreadsheet later, I have tried but it is brutal on my iPad.


  1. Not sure if they wait for all water to be absorbed or if they wait for the previously applied amount to half absorb and divide Asa / 2 to absorb. Time could be saved with the ladder, I think?

I agree. So I tryed to cross reference with other sources:
Rachio: What Is Smart Cycle

WaterSense Specification for Weather-Based Irrigation Controllers (PDF)
This article references AI-CLIA Training Manual Pg. 73 (September, 2004) but I don’t have or can’t find a copy.

Contacted our local IIABC and they say they use 60 x (IR/PR) in their online calculator.

Found copy of Certified Landscape Irrigation Auditor Training Manual (The European Irrigation Association) (November 2013), but also uses 60 x (IR/PR). Speakes of slope being important but does not reference ASA.

Anyone know a IA Auditor?

No reference to ASA in the Certified Landscape Irrigation Auditor Examination Equations from Irrigation Association Landscape Irrigation Auditor, 3
nd Edition (February 2013).

I would spend more time looking at turf manager resources. university of auburn and uga are excellent resources as well as penn state. Asa is a concept you can read about in hunter and rainbird irrigation smart water documentation and it is very important in the more modern efficient irrigation controllers. If you like I can post some other links. But if you lookup pace turf and look at their you tube videos, you find names like mihca and John which you can use as rabbit holes and find some excellent cutting edge info.

But in short Asa is the amount of water that can sit on the surface of the soil based on the elasticity and surface tension of the water. This can be impact my many different variables, most of which the Iro is not concerned with as healthy soil should be with in the margin of error

Edit: I hate autoincorrect

Also, with talking to franz, you have to understand that they have opted for more conservative numbers. Their ir is smaller which only means that extra efficiency is gained. They always opt for the more conservative numbers as the vast array of yard types require more conservative numbers at different times.

2 ppl with tif 419 in clay with the same slope will have a different asa if the ph of the soil is different.

So take the most common denominator.