Run Time Increased massively after configuring advanced settings


I know this is a topic discussed ad-nausea here but I’m still stumped at what happened to me.

I’ve been using flex monthly for about a year with the default settings in the advanced area. Most of my zones would run for about 9 minutes pretty much every day.

I followed the steps in:

I chose sandy loam for my soil since it is a new build, but the general soil in the area is flagged as gravelly loam so I figured that was the closest match.
The turf is mostly bluegrass and fescue so I left it at 6in depth since my research showed that fescue can get pretty deep.
I left the available water and efficiency alone and changed the Kc to 70% (based on what I researched)

however, instead of doing the catch cups, I measured out the area of each zone and got the GPM from my water meter. For a number of my zones, it drastically lowered the PR down to .5 or less (instead of the normal 1 or 1.5

these adjustments moved my flex monthly schedule to run for almost 350 minutes now (starting at 11 pm and running until 6 am) and flex daily would be over 550 minutes!

  1. does this sound right? was I watering my lawn wrong this entire time
  2. Am I getting accurate PR’s with the area and GPM calculation, my rotors are not all doing 360
  3. I’ve seen a few other threads that recommended that I start with a shorter root depth and work my way up since I’ve probably had it too shallow for too long

I’m trying to balance having a great looking lawn and having a wife that won’t kill me for a zillion-dollar water bill. :slight_smile:

What is Kc? (I’m still getting used to the terminology; some use different descriptions.) What all values changed, and to what?

I’m planning on doing catch cups on Sunday, but I also measured the area and GPM and calculated PR for my zones. I got values between 0.33 and 0.96, but all below the “suggested” numbers. And I have a feeling I’m high compared to what my catch cups will find.

How many zones. We can’t compare 9 minutes per zone with 550 minutes. What was your flex monthly schedule total time before? Knowing the change in the variables, it should be easy to calculate the difference in total water applied and water applied at once.

All good questions. I’m about to find the same thing out.

Hopefully these figures are accurate. At least on average. There’s bound to be variations though.

I’m thinking you have been watering too often, IMHO. Daily, even at this time of year, is not great for the grass. The top surface should have a chance to dry out, drawing oxygen to the roots, etc. 2-3 times a week sounds better to me.

Aren’t we all!

Crop Coefficient. I left available water at .12 and efficiency at 70% those seem to be calculated based on the soil and sprinkler head i picked.

How many Zones?

Sorry, i have 8 zones. Previously with my old settings, it was running for 69 minutes total.

I’m thinking you have been watering too often, IMHO. Daily, even at this time of year, is not great for the grass. The top surface should have a chance to dry out, drawing oxygen to the roots, etc. 2-3 times a week sounds better to me

I’m also thinking that, but it been pretty warm in upstate NY this summer. I would assume the flex monthly would have accounted for that.

Flex Monthly schedules use historical weather data not current weather data. So Flex Monthly schedules will not adjust dynamically based on current conditions.

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Correct. Plus: It always waters all zones on the same day (Flex Daily usually doesn’t water all zones on the same day, but spaces them out more), you have no feedback like you do with Flex Daily as to how and why it’s doing stuff (the Field Capacity graph and chart), and Monthly is still dependent on all the variables we complain about with Daily. To me, it’s an easy decision for Flex Daily.

Oh, and it’s surprising how much the daily ET (Crop Evapotranspiration) varies per day. It’s been just HOT here in SC lately, but Tuesday it was 0.22 and today 0.14. That means that earlier this week , 57% more irrigation water was required than now. This is an important benefit to Flex Daily, not wanting to over-water, nor stress my grass with too little for the heat.


Let us know how the catch cups compare to your area + gpm measurements. That will help me gauge if i want to do the catch up cups too. I can’t find them in stock anywhere so i’d rather not have to wait forever to do that.

You’ll find the results of my testing in My First (and Probably Last) Catch Cup Experience. They were NOT good. Not only were my catch cup values all over the place (really low efficiencies), but the total area calculated from them was nowhere near my actual area. Or put another way, the Precipitation Rate (Nozzle Flow) calculated by both methods were different. The flow based on Area & Gallons was 12% to 71% higher than what my catch cups measured! And yeah, while catch cups can’t be wrong, their location can be. With mine all over the place, and being able to very accurately measure the actual square feet area of each zone (using my CAD drawings, confirmed with Internet views), I’m using them and abandoning my catch cups.

If you think about it, IF you can measure area accurately, it is a far more accurate method to get AVERAGE flow over your zone. So that’s what I’m using.

that’s my thought. i moved to flex daily for my front lawn and was some longer runs but only twice all week. the lawn isn’t puddling and the ground isn’t dried out either. the sprinklers overlap a lot but the layout is pretty evenly distributed. i’ll probably try up front to see if they match. my zones have a ton of overlap so that’s my only thought that i may be laying down more water than i need.

If your irrigation is even across a zone, your catch cups should be fairly constant, and thus calculated Nozzle inches ought to be as well. Given my case, where they vary so much - not so much.