Flex Daily Total Run Time Adjustments

Schedules & Zones
21

Since you are talking all grass, you are safe to assume that you are going to be silty loam, which can have anywhere from .16-.19in/in, so I don’t know that your .17 is far off…

I would say that since you watered with short durations, more frequently that you needed to, that your root structure might even bee shallower than default. Personally, I like to adjust root depth to change duration and frequency, because for me, it is a visual thing. If you set your root depth to say 4" for now. This should decrease duration a bit, but up frequency.

The nozzle PR will need to be figured out either by the meter read and calculate method, or catch cup. If your sprinklers are putting down significantly more than you think, then your duration will come down, possibly to where you think needs to be.

Like @rraisley has said before, you need to look at the long term here, and see if you can see the savings. Short term, it might look like the durations are longer than you think they should be, but Rachio is going to adjust and water less frequently than you might expect.

Once we dial these settings in, if you feel happy with the look of your grass, and want to maximize savings, you can adjust crop coefficient a bit until you get to where you feel comfortable with the grass.

As a reference, I have rotator NOZZLES (not rotator sprinklers), and they are a very low PR, and my grass zones will run for 58 minutes each, but even in the dead of Arizona summer, they will run every 2-3 days.

22

The soil survey site said that my Available Water was anywhere between .19-.22 based off how deep I was setting roots. Do you think I should leave at default of .17 or drop down to .16?

I think I am fine with leaving root depth at 6". I’m ok with keeping the duration where it is as well as the frequency. I think the way I have it setup now with the shade setting and the .25 increase on both my nozzles have it dialed in pretty good. I guess we’ll see for certain as time goes by.

My next step is trying to figure out what to do about the weather. I’ve seen some say that switching to a PSW is better than keeping the default WI+. I have two stations .29 miles from my house. My only concern is the stability of the stations, how accurately they’re setup and the upkeep. Without getting a rain gauge and comparing it to the two stations near me as well as the WI+, I’m not sure how else to make a conscious decision whether to stay with the default WI+ or move to a local PWS.

23

I’m trying to better understand the Soil Moisture functionality. If the system runs at set default time, is the goal for the moisture to reach 110% after each run? Two of my zones ran over night at the default times (17m duration for fixed heads), but only reached 76% soil moisture. Is this by design or should I expect each run for every zone to hit the 110% threshold upon completion?

24

If the web soil survey is saying AW is .19-.22, I’d set it there. I wouldn’t go further in the opposite direction. This should mean that the soil can hold more water, so the system will should run less frequently, but you might see a slight bump in duration.

I always recommend a solid reporting PWS over WI+. WI+ is great for areas lacking PWS options. When selecting a PWS, you can look at the reporting history of the PWS for rainfall, temps and wind. Make sure you find one that follows weather patterns at your house. At the end of the day, localized rain is going to happen, and the PWS will never be 100%, but much better than WI+. Only thing better would be to invest in your own PWS and get it on the WUnderground network so you can read from there!

It won’t always take it to 110%, in fact, it probably won’t hit that very often. It is more concerned about keeping it from dropping below zero.

25

The system will not normally (or ever?) run to achieve 110%. It’s designed to run to 100%, assuming early morning watering, but the graph and chart shows the moisture at the end of the day, after the ET value is used. So with 76% moisture, it could have watered to 100%, then the day’s heat used up 24% of that.

110% is normally achieved just when the rain water received exceeds the capacity of the soil, and they max it out at 110%, assuming the rest will run off.

26

Thank you very much for all of your help here. You’ve helped me a TON!

I looked into purchasing a PWS recently, but didn’t realize all of the hassle that comes with physically setting up (factors relating to location, shade, sun, etc.). I just received an email survey from Rachio on interest in their own PWS. I’d 100% be interested in an integrated PWS.

In the meantime, I’ll research my two local PWS near my home (0.29 miles away) and made a decision on one of them rather than keeping my WI+.

I’ll also look into changing my AW from default .17. Quick question: when looking at web soil survey, should I mark the bottom depth of my roots at 6" since I only have grass (tall fescue) that I am watering? If I set at 6", the AW jumps to .22. If I change to 40", it goes to .20.

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27

I changed my default from .17 AW to the .22 that web soil suggested. My total watering time per schedule went fromt 2h 34m to 3hr 19m. Over the next 10 days, it reduced one watering day.

Over the next three weeks, my default setting of .17 will run for 15h 24m vs the updated AW of .22 for 16h 35m.

It looks like the best option is to just leave it at the default setting of 0.17.

28

I still don’t think you’re fully understanding what Rachio is doing.

A longer runtime doesn’t equate to a higher water bill for you.
Your AW is how much water your soil can hold for every inch of soil. So if you have 0.22 in/in AW, that means your 6" depth can hold 6 * 0.22 = 1.32" of water. If you’re allowed depletion (AD) is set to the default 50%, that means that Rachio will drop 1.32" * 50% = 0.66in of water every time it waters.

For 0.17, Rachio will drop (6 * 0.17) * 50% = 0.51in of water every time it waters.

Hence, the increased runtime.

But just because you have increased runtime, doesn’t mean you will use more water over the course of a month. With a higher AW (0.22), you’ll water more at one time, but it will water less frequently. With an AW of 0.17, it will water less at one time, but more frequently, but the water over the long-term will remain the same.

At this point, it seems like you’re tinkering with numbers just to get the watering times down to what you think they need to be without thought of how the water is applied over time. There’s a reason Rachio is called a “smart” controller. Let it be smart.

For comparison, like a user above, I use rotary nozzles for my 3 zones. I have clay soil and an AW of 0.18 with cool-season grass. My runtimes are:
Front lawn: 1h16m
Rear lawn: 59m
Pool lawn: 1h25m

These are all based on actual usage data via a catch cup test, not guesswork.

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