[yellowgecko]

Hi Ray,

thanks a lot for the detailed answer. As you may have seen I progressed a bit with my approach using ETO and weather. I fully anticipated it to be an open hardware/source project so really happy with it.

Cheers, Bernd

[yellowgecko]

Same here no more weather forecasts. [Where not too usefull anyway as they did not show precipitation in terms of mm or so]

[yellowgecko]

Okay I think I have an idea how to do that.

First I needed to understand how the %watering actually works. The Zimmerman is simply changing in the end in a sophisticated way the value and does this just before the start of a water event. Regardless the switch: use weather adjustment means that a program takes the %watering into account. So if the %watering is changed manually (but not by a weather adjustment method) the watering times are still adjusted if the value is not 100%.

Hence it is quite simple. Run a cron job that monitors evapotranspiration and changes the %watering via an api call.
e.g. http://ipadress:8080/co?pw=mypassword&o23=77 (sets the value to 77%).

So I think what should work beautifully is the following:

Set the sprinkling system to a regular schedule that waters you garden with say (just an example)

10mm of water every 5 days which refills it to 100%

Everyday, check the evapotranspration up to the last sprinkling event and if it is above 10 mm then water back to the 10 mm level.

If during the 5 days the sum of evaporation was below 10mm we again fill up to 10mm. (only what is really needed)

If levels are getting low but forecast has a high chance of rain in the next 24 hours we wait.

Best would be here to have a rain sensor to check if it has rained.

Finally if it rains we “reset” the schedule and start to count the 5 days again (amount of rain needs to be above 10 mm, if this is the reference).

So we simply need a script in say python that grabs all the bom data and changes the water levels/times according to those rules.
A minor difficulty is that there seems to be a lag from the BOM data (the evapotranspiration for the day before is not available before 3 pm afternoon the following day). So there needs to be some buffer in the fill ups to cover that half day.

One more (maybe stupid) question

When is the best time to water (early morning or later in the evening)
I thought in the morning just after sunset, but not sure where I read that.

Cheers

[yellowgecko]

Hi Ian,
thanks for the reply. Thanks for the kind offer, happy to come over at some stage when I am around. And also thanks a lot for the explanation on the Zimmerman. so it does not make sense to water in the morning using it with the current setting. I think even the current table of bom with Eto would be a great improvement. I am just struggling how to “intercept” the water level request. I try to find the bit in the code where it updates the watering % just before it runs the program. My idea is to have a cron job running that download the bom table once a day (or every hour) and then use it to calculate the %watering. As I said I still have not found a good way to intercept/replace the watering calculation. Must be somewhere in the main loop. There is a getweather function, but still not to sure how to realign it to another script.

PS. YOu mentioned earlier that you use the Zimmerman algorithm. Can you let me know your setting, meaning when do you water and what are your humidity, temp and rainfall setting and sensitivities.

Thanks again,

Bernd

[yellowgecko]

Hi Ian,

i just saw your mails and i assume from your links that you are also located in Canberra. I have an OSPI connected and started to look into the Zimmerman method (got it two weeks ago). You seem to have adjusted the Zimmerman values and it works for you.

My program scheduled in the morning at sunrise does not really work. are you willing to share your values that would be great. i will also have a look if we could use bom data from your link, that would be even better.

btw. i am in Evatt.

Cheers, Bernd

[yellowgecko]

just tested it:

(parseInt(“-“)+1+2+3+4+5+6+7)/10

results in NaN
so if there is a missing value temperature, rainfall etc. are not defined…

[yellowgecko]

Hi admittedly I am not sure if I searched at the right position. I tried to find the position where the weather data is downloaded.

If I am not mistaken the adjustment for the openweathermap data is done in the OpenSprinkel Weather javascript (hosted on Amazon).

The latest fix is called “Average out the incoming data from OpenWeatherMaps” and was done 4 month ago.

Here I find the following api call to owm:

forecastUrl = “http://api.openweathermap.org/data/2.5/forecast?appid=” + OWM_API_KEY + “&units=imperial&lat=” + location[ 0 ] + “&lon=” + location[ 1 ];

which is a forecast the next days (3 hourly up to 5 days).

THen the temperatures, humidity, rainfall etc. are averaged across the first 10 entries (which essentially is 30 hours). A potential problem here is that if a data point is missing, hence as the algorithm sums over values if NaN is added then at least the denominator of 10 is false, but not sure if that does not lead to an NaN overall.
There is also a comment by tekshed that this might be a problem.

Finally I am also a bit puzzled that the forecast data is used here. Zimmerman relies on the previous data not the future data, but not sure if this call is also used by the Zimmerman algorithm.

So potentially here could be the problem (wrong averaging if data is missing (NaN)) and also using forecast instead of historical data.

Anyone out there with a better understanding that might be able to have a look at it.
github link to the commit

[yellowgecko]

Same for me. Was a really hot day and %water is down to 0%. The idea that it only takes the current temp, rain and humidity mentioned in August in the forum:

https://opensprinkler.com/forums/topic/weather-adjustment-using-current-temperature-instead-of-average/

seems to be true [rather what it is supposed to be used is the average of the previous day].
[[Best would be actually the average across the days since the last watering was performed]]

The forum never reached a conclusion but Ray said he would look into it.

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