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Help Irrigating with Evapotranspiration


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I have a 1/2 acre vegetable garden with 24 irrigation valves controlled by 3 Ez-Flora's & and an ISY99. Our crops range from carrots to Tomatoes & Peppers which all have very different requirements as far as irrigation goes, so, in prior years I have used a program for each valve which runs for a set amount of time based roughly on the requirements of each plant (i.e. if crop X on Valve 1 needs 1 gallon, operate valve 1 for 2hrs, if Crop Y on valve 2 requires 1/2 gallon then operate valve 2 for 1hr etc..) - I based the run times on the estimated plant requirements for a week, for example, if my tomatoes need 3 inches per week I could either run the program for X amount of time 6 times a week, or for Y time 3 times a week but it isn't that simple due to changing heat and wind paterns here in Northern California. Some times plants were over watered using this method, other they needed extra. Ultimately though, a lot of water was wasted irrigating on fixed days rather than just when the plants need water, which is why I oped to try the ISY Irrigation module.


Anyway, I have now purchased the ISY irrigation module and I am hoping desperately to be able to create DAILY programs that vary the length of runtime for each valve daily based on the ISY's Irrigation Needed data. For example, if I know 1 inch in ISY Irrigation Required = 1hr Valve runtime (I know it isn't 1:1 I'm using that to explain what I'm trying to achieve), then after setting the IF On time (i.e. 2am every day) I would like the program to activate at 2am then act upon the ISY data, turning the valve on for 1hr if 1" of irrigation is required, half an hour if half an inch is required or 2 hours if 2" is required etc...

When Valve 1 completes it will run the Valve 2 program so on then the final valve program will 'Complete Cycle' and be ready to collect data the following day.


Has anyone tried to accomplish this yet and if so, could you please point me in the right direction? I have been searching the forum and found mention of people 'going to try' with the new module but as yet I haven't been able to find any example programs I can modify for my needs.


Thank You in advance for taking the time to read this.





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Hi Mark,


Unfortunately ISY does not do multi-zone calculations.


There are a few things about the irrigation module that you should know:

1. The amount of water applied per cycle is 100% up to you. If you wish, you can make that a very small number so that the program is called multiple times to water

2. Actual Water applied is dependent on absorption factor ... since you have 10s of different zones, I am not sure how this would work


With kind regards,


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  • 1 month later...

Here's my solution to irrigating different zones that required different watering requirements. Your question was automatically adjusting irrigation times, I don't have a program set for that exact scenario. This doesn't automatically adjust how long to water your different zones, but allows you to water different zones at different frequencies. Hopefully it might help in your case or at least give you another idea to try:


I have 3 zones in my setup and 1 Variable:

1-Cycle Zone

2-Cycle Zone

4-Cycle Zone

IrrigationCounter variable


Essentially, 1-cycle zone is for ETo of 0.5, 2-cycle zone is for ETo of 1.0, and 4-cycle zone is for ET0 of 2.0


At the completion of 1-Cycle Zone, it runs the "cycle complete" command, adds +1 to the IrrigationCounter variable, then runs the "if" 2-Cycle Zone (which runs only if the IrrigationCounter is 2 or 4).

When 2-cycle zone runs, it triggers 4-cycle zone, which only runs if the irrigation counter is 4.

At the completion of 4-cycle zone, it resets IrrigationCounter to 0.


I'm open to comments of suggestions to improve my irrigation program set.


1-Cycle Req Met

       Time is Sunrise -  2 hours 
   And (
                 Module 'Climate' Irrigation Requirement > 0.5 inches
             And Module 'Climate' Rain Today < 0.1 "

       Run Program 'Run 1-Cycle Sprinklers' (Then Path)


Run 1-Cycle Sprinklers

  - No Conditions - (To add one, press 'Schedule' or 'Condition')

       Set 'Landscape / Irrigation 1-2: SideStripLawn' On
       Wait  15 minutes 
       Set 'Landscape / Irrigation 1-2: SideStripLawn' Off
       Irrigation - Cycle Complete
       $IrrigationCounter += 1
       Run Program '2-Cycle Req Met' (If)


2-cycle Req Met

       $IrrigationCounter is 2
    Or $IrrigationCounter is 4

       Run Program 'Run 2-Cycle Sprinklers' (Then Path)


Run 2-Cycle Sprinklers

  - No Conditions - (To add one, press 'Schedule' or 'Condition')

       Set 'Landscape / Irrigation 2-6: Mango, Orange' On
       Wait  3 minutes 
       Set 'Landscape / Irrigation 2-6: Mango, Orange' Off
       Run Program '4-Cycle Req Met' (If)


4-cycle Req Met

       $IrrigationCounter is 4

       Run Program 'Run 4-Cycle  Sprinklers' (Then Path)


4-Cycle Spinklers

  - No Conditions - (To add one, press 'Schedule' or 'Condition')

       Set 'Landscape / Irrigation 2-1: Succulents' On
       Wait  15 minutes 
       Set 'Landscape / Irrigation 2-1: Succulents' Off
       $IrrigationCounter  = 0

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