Bucket Calculation Isn't Going Negative

[andrewgl504]

Did you read the docs?

• I read the docs and my question is not answered there.

What happened?

The documentation and UI for the irrigation integration state that the bucket value can be negative, which indicates irrigation is necessary. However, the calculation example provided in the integration’s explanation provided by the "information" is confusing and appears inconsistent:

This is a verbatim copy and paste. I've bolded and italicized the part that's confusing. I expect a formula of 25.4 - 187.16 = −161.76. Instead, it's returning 0.

Note: this explanation uses '.' as decimal separator, shows rounded and metric values. Module returned Evapotranspiration deficiency of 155.95. Bucket was 0.00.
Maximum bucket size is 25.4.
Drainage rate when saturated (bucket at max) is 12.7.
Current drainage is calculated as [drainage_rate] * [hours] * (min([old_bucket] + [delta], [max_bucket]) / [max_bucket])^4 = 12.7 * 14.74 * (25.40 / 25.4)^4 = 187.16.
New bucket value is min([old_bucket] + [delta], max_bucket) - [drainage] = min(0.00+155.95, 25.4) - 187.16 = 0.00.
Since bucket >= 0, no irrigation is necessary and duration is set to 0

We've had a lot of rain lately, so I haven't had many chances to test, but I haven't been able to get a duration > 0 even on days when I would expect irrigation. So I'm not sure if it's just the information example that's wrong, or if it's something bigger.

How to reproduce

1. Set up a zone as in the screenshot (see below).
2. Click Calculate.
3. Click Information.

Relevant log output

I enabled debug logging, then manually updated All (2) zones, calculated 2 zones, then disabled logging. That entire log is attached below.

Which version are you running?

v2025.7.2

Diagnostics file

• I have attached a diagnostics file

Additional information

Diagnostics File

Debug Logging

[Besarmatis]

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