First thanks to everyone who has responded to my other posts, to the forums for their excellent Search system, and to Rachio for providing a lot of technical information. I think I understand what I need to for now, and have tuned my schedule to where I think it will work for me. During that process, here’s what I’ve found:
I’m using Flex Daily, as it responds best to temperature changes, as well as rain and other conditions. I’m really quite impressed that if I do Test watering (for catch cups), or add a bit of water here or there, that Rachio knows and remembers all that and includes it in the day’s moisture analysis.
I’m in Columbia, South Carolina, and have confirmed that the Available Water per Inch of soil is 0.17, which is what Rachio entered for Clay Loam. I confirmed this based on land survey information online, so that’s good.
Naturally, I selected Warm Season Grass, and here, I think, the program could use some improvement. There is a LOT of variation in warm season grasses, from Centipede (which I have) to Bermuda to St. Augustine, etc. For Warm Season Grass, Rachio gives a 9.84" Root Depth and an 65% Crop Coefficient. But sources indicate that Centipede has 6-8" root depth and an 85% Crop Coefficient. Making those changes in the Advanced screen (I chose 6" root depth to start, and can increase it if I feel it’s not enough) reduced water application per cycle by 40%!
For now, I’m leaving the Efficiency at the default, and have manually changed the Nozzle Inches Per Hour to my manual calculation based on area and water usage. I will change both to “actual” values after I do my Catch Cup testing (delayed because I have some known problems in that area).
I am 100% convinced (okay, 80-90% at this time) that adjusting watering amount should be done with the Root Depth value. Changing it is /directly/ proportional to the maximum water applied per day. Double it, and you’ll use twice the water. Decrease it by 10% and you’ll use 10% less. Now that’s per watering cycle, and there may be some variation in frequency, but it’s less noticeable than soggy grass. I won’t say that adjusting other factors can get you to where you’re going, but I have faith that Rachio knows a lot about watering amount and frequency, and can calculate that part fine. What they don’t know is how deep /my/ root system is, nor how /my/ soil affects it and the water it can hold. Adjusting Root Depth seems to take care of that.
I will interject here that IMHO the WORST adjustment a person can make is changing the watering TIME. That takes away all intelligence of the inherent code, and you’ve turned the system into a manual system. If you KNOW the time is off, change Root Depth or other variables to correct it.
So, I now have a darn soggy yard, from 3 days of over-watering (and Rachio knows it - on the graphs), with my new settings, and I think I’ll be close going into the future. I may need to increase the Root Depth as we go on, but it should be easy to manage. Were Rachio wanting to have a More Dry <> More Wet slider, I think if it simply modified the value of Root Depth used in the calculations (not displayed), that would satisfy most people. Until then, I’m happy to adjust it.