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    Hi all,

    I am new to OpenSprinkler. As a first project, I equipped my huge balcony with Gardena Micro Drip and Opensprinkler so my bamboo and tomatoes can survive the upcoming holiday without somebody driving to my house ever day 😀 Because that is how thirsty they are. Sometimes two times a day. I also have upcoming plans to use rain water from a barrel when available, however thats not topic of this post.

    So I experimented with Zimmerman and eTO and read a lot about the methods here in the forum and docs. Generally I understand how all this works but in the daily use a question emerged about the behaviour of the eTO method.

    I first tried Zimmerman but didn’t like it and then switched to eTO which is feeling much better. Let me first describe my settings to help you understand my upcoming question better:

    I attached a Hunter Rainsensor to S1 to stop watering when it really rains and not when the weather report thinks it might be raining. This is working good so far.

    Next I set the circuit to “Ignore Rain” (I assume this option means the rain from weather reports as the Sensors have own options. Left my rain sensor active of course).

    My eTO baseline is 2,5mm for my location according to the app and I left it like that, altered the height as it was wrong (100m now instead of 185m).

    I water for around 3mins (still playing a little bit with the time) at 6h, 14h and 22h and how eTO alters the watering time seems to fit quite good in most cases. Dark Sky also seems to have quite accurate information for my area.

    Now my question:

    With the eTO method this was doing quite well for a few days and also right now. However there was one day where it completely failed. It was raining the whole night and the morning of the next day, maxbe until noon. eTO set the Water Level to 0%. Might have been reasonable for a garden situation. But bamboo and tomatoes are really thirsty bastards, especially when they live in a pot. When it is raining untill 11:00 and then it becomes cloudy but 26° for the rest of the day it is just not reasonable to cancel BOTH upcoming waterings for that day (the 14h one AND the 22h one). But thats what happened – water level 0% / no waterings scheduled for the rest of the day. My tomatoes were begging for water and I would have been okay to let them wait until 22h, but not until next morning. I played around with the eTO baseline, but no matter how high or low I configured it – it planned to give 0% water level for the rest of the day. Any way to overcome this behaviour? Maybe by giving the possibility to enter a minimum water level? You may say “but then it will even water when it is raining?”. No it want, because the rain sensor will cancel that out.

    Another thing I could think of would be using more accurate weather information. I read that OpenSprinkler caches the weather information of the last 24hrs and therefore it will not change over the day. So I still have a DarkSky API key – can’t I enter it somewhere to allow my OpenSprinkler to get weather information three or four times a day?

    Thanks in advance for your input!



    First, to clarify: ‘Ignore Rain’ does NOT mean rain from online weather data, it means the manual rain delay that you manually trigger through the UI. This is explained in the firmware 2.1.9 user manual:
    just search ‘Rain Delay’ in the PDF.

    Ignore rain sensor is now called ‘Ignore sensor 1’ or ‘ignore sensor 2’ depending on whether you connected rain sensor to sensor 1 or 2.

    Next, I am confused whether you do want your bamboo and tomatoes to be affected by watering percentage, or you do not want them to be affected. Generally I would imagine if you put them on your balcony, maybe you do not want them to be affected by watering percentage. If so, you should go to the programs and un-check ‘Use Weather’. If you want them to be affected by temperature and humidity, but not by rain, you can choose Zimmerman algorithm and give 0% to precipitation.




    thank you for educating me about that Ignore Rain function, must have overread that. Ignore rain sensors is pretty clear and I have that turned off.

    So regarding my question: I want them to be affected by all the factors Eto takes into consideration. It is working quite good almost every day. I tried both, Zimmerman and Eto for a while and 99% of the time it is just working great. With the rain sensor it is also working fine.

    But that one day it was not ok. And I suspect the fact that the weather data is only updated once in 24hrs (that is correct, or not?) as teh reason. If it is raining the evening before, the whole night and today until 10am and then it becomes 26°C the rest of the day, I just don’t want him to cancel out the 22h watering. Maybe the 14h one, ok, but even the one in the late evening after such a warm day? In the garden that might be sufficient, but not for plants that reside in pots. It would either be great to be able to take more current weather data into consideration or at least create some additional rules like “always water at least X% when temperature exceeds X°C”.

    The second thing is that I read about modifying the Eto baseline to adjust watering, however no matter what I entered, lowest or highest value, it was not changing to anything higher than 0% that day.

    Of course I could create an automation in Home Assistant or Node-RED that checks how hot it is and starts watering through the API in the rare cases where it is hot and the Water Level is on 0%, but I would like it more to have the OpenSprinkler itself being able to take care for everything.

    For now, if there is no way to use more current weather data for Eto, I will continue observing, as this happened only once. However I think when I have an Internet connected Sprinkler, recieving hyperlocal weather data, it would be great to be able to use more current data than from a 24hr cache so it can adjust to strong changes in weather like that day.



    Since that one incident I am quite happy with the watering until today. I guess I will just observe for a while and see if it stays like that 🙂

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