Moisture Levels Confusing


#1

I’m confused. my flex schedule was set up to run last Thursday but I felt it did not need it due to precipitation so I put a rain delay in until Friday since the moisture for each zone was over 100%. The calendar showed that it would skip the Thursday watering and continue on Sunday. This seemed to be exactly what I had wanted it to do.

Now its Saturday morning and I wake up to the notification that it ran the full flex schedule, instead of tomorrow as the calendar showed last night. Now I understand that the calendar changes and I can deal with that, but i don’t like how the predictability is gone. I would like to check the calendar, and expect what I see to happen barring precipitation. This isn’t the case.

Here’s the most confusing part. Yesterday the moisture level for my zones was in the 60% range. Today, after a full watering, it is 53%. How is this possible? Now it wants to water again on Monday already! Just a couple days ago the level was over 100% due to rain, but now the sprinklers cant increase it at all?

So far I have tried as needed and flex schedules, and they change so much, most of the time the changes make sense, but there are consistently things that make me scratch my head. One thing is clear, I am having to pay so much attention to the system to make sure I’m not using even more water than I did with a dumb controller.


#2

Can you post a pic of one of the moisture level graphs with details of one of the zones you are questioning? That would make it easier to explain. And can you also post what you have your MAD set to for that zone? (If you left it at the default it will be 50%)

It took me awhile to understand the moisture level details, but once I got it they are fairly easy to read and know just why it wants to water or not.


#3

Here is a screenshot of the last week. FYI this zone MAD is 50% and the efficiency is only 30% since I don’t think my system is full equal coverage. I guess the levels aren’t what I thought at all. They are way lower! I am even more confused now!

My sprinklers ran the full cycle this morning and the the moisture level only got up to 58%, now currently is all the way down to 11%. How am I supposed to keep up with this system, its as if it will want to run every other day to keep the moisture up.

Thanks for the help.


#5

I am fairly certain that you can only access moisture levels if you are currently using a Flex schedule, As Needed schedules do not show moisture levels.


#6

What are you watering? What are the vegetation and expose settingd and the associated crop coefficient? If you’re expecting less frequent watering then the evapotranspiration estimate is likely higher than you expect. The settings above effect that.


#7

@CH-Johnson. By the way, if you don’t want to be surprised by a watering shift in the calendar, you’ll want to stick with As Needed. I believe that was one of the main goals of that algorithm. At worst it will skip a scheduled watering if it thinks your vegetation has enough moisture to last until the next scheduled watering. There might be a calendar shift from month to month, but otherwise you won’t see the kind of changes you see in Flex. And I think your right that as it is now, As Needed doesn’t have moisture graphs.


#8

Vegetation is Bermuda in clay soil. Crop coefficient is 65% and root depth is 6 inches. Full sun with variable slope depending on the zone.

I have tried as needed, but I didn’t like how it skipped watering a instead of postponing them.


#9

I have similar settings on Bermuda and predictions are for watering are every 2 or 3 days for 23 minutes. That’s about normal for out here in the desert. What were your expectations? By the way, I have a root depth setting of 9 inches.


#10

The rain delay that you had through Friday appeared to work (I just learned something new as I didn’t know rain delay worked with flex schedules – part of running a flex schedule is for it to determine how much rain you got and you not to have to worry about setting something manually). This zone watered on Saturday, May 7 because the Current Moisture Balance (think of it like a gas tank for your soil) was totally empty. So it put some gas in the tank. Since the day isn’t yet over, it still says Forecasted, and based on weather parameters, and what you’ve told it about your soil and plants, it’s going to predict to empty .19 inches out of the gas tank. About an hour before your schedules are set up on Sunday, it’s going to go out and look at the weather forecast again, and also calculate what actually happened on Saturday (perhaps you got rain that wasn’t in the forecast, or a different amount of rain than was predicted.). Since it’s taking all these changes into consideration on a daily basis, the “schedule” of when it’s going to water next is just an estimate, and is subject to change (just like the weather!).

The rain that you got on May 5 was only .12inches – that’s not a lot, but since you turned on the rain delay, you thought you had a lot more? From the name of the weather station, its not a PWS (Personal Weather Station). Is it a long ways away from your location? You might want to go in and see if you can find a PWS closer to you that might be more accurate.

The reason it’s got to keep watering more often is that even though you filled up the gas tank, you also drove and used up almost half a tank of gas (this zone watered .45 in, but between the weather and the plants using the water, it used up .19in.). So the 58% full makes sense. On Sunday, you’re going to drive the car around some more, but not put any more gas into it, so you will be down to only 11% in the tank. If there is no rain in the forecast for May 9, based on the ET this zone is using every day (from .12 in to .21 in), this zone is going to need to water again on May 9.

I hope I haven’t confused you more, talking about the gas tank and the water all at the same time. But it is a great analogy to help understand it.


#11

@Linn I really appreciate your explanation. However I do completely understand how the moisture levels work, I was mostly confused at how fast it is depleting, especially since the sprinklers ran this morning. They will already have to run 2 days later. If it’s this bad already how often will it run when it gets hotter in mid summer?

I am supposed to be watering 1 inch per week, and less often deeper waterings are better, so why is it so often? Why isn’t a run through of the sprinklers enough to raise the moisture back up to where it needs to be?


#12

Look at the crop evapotranspiration. Something has changed in your weather just in the last few days. You were around .12-.14 inches, and the last two days you were at .19 and .21 inches. If your weather stays like this, you are going to be needed to water roughly every other day to keep up.

I would monitor it for a week or two to see what is happening and how your grass looks. You might want to do a catch cup test to see what your actual efficiency is. 30% is really low.


#13

Well the default is 70% I believe. I messed with it at around 50% and it wasn’t really changing anything so I ended up at 30% but only for 2 of my 5 zones.

Again, why would it have to water every couple days?


#14

Efficiency does changes to the amount of time it takes to water to get to the inches of water it needs to put down. I tried a test zone, and only changed efficiency. I did Cool Season Grass, Clay, Moderate slope, Some shade and rotor head. At 70% efficiency it was going to water for 33 minutes. At 50% for 39 minutes, and at 30% for 47 minutes. All three of those waterings would produce .45 inches of water being put down and show up as .45 inches on the moisture level chart, even though the times are very different.

The way you have things configured right now, it takes .45 inches of water to get you to field capacity. So the start of May 7, there is .45 inches to use. During the day on May 7, between the temperature, the wind, the humidity (and other factors) and what the plants are actually going to use, the zone is going to eat up .19 inches, leaving you with .26 inches. So on May 8 you start with .26 inches. But the weather on May 8 is going to use up a little more, .21 inches this time. So now you only have .05 inches left. It needs to water again so you don’t go down to 0 inches. This is all with your MAD set at 50%.

My apologies if I’m still not answering your question. I’m trying to figure out what is causing your confusion, and I may not have hit on it yet.


#15

Again I appreciate your answer and I understand what you are saying.

I will adjust my efficiency to a more reasonable 50% but when I say I’m confused, I mean in general about the watering practices of the system. If you asked an authority in my region, say Walter Reeves, he would say to water an inch at a time per week. There is no way he would say to water every couple days. This is my confusion. Why doesn’t the schedule put down more water at a time instead of having to refill the “tank” so often?

My main concern is that I will constantly have to monitor the system to make sure my water bills are not skyrocketing, and to figure out if I agree with what it’s doing.


#16

Here are a couple of links from the Seasonal adjustment thread that describe the methodology used in Flex from resources other than Rachio.

https://www.rainbird.com/landscape/resources/webinars/ManagementAllowedDepletion-IrrigationScheduling.pdf4

http://extension.colostate.edu/topic-areas/agriculture/irrigation-scheduling-the-water-balance-approach-4-707/

Flex is not for everyone. You may end up not running it.