Oh this is definitely super geeky. I use a Tilt Hydrometer (Here is NB’s page, but others sell them too.)
- The Tilt floats in the fermenter.
- Raspberry Pi runs their TiltPi software. One Pi can monitor multiple Tilts via Bluetooth.
- TiltPi periodically adds Rows to a Google Sheets spreadsheet. Every 15min IIRC.
The screen grab is from the spreadsheet.
Anyway, I don’t know that the Tilts are super accurate, there is a whole calibration process but the calibration gets stored in the reader side, not pushed to the Tilt, so you can get different readings from the same device depending on whether you’re on the local TiltPi page, or from the app on your phone. I don’t use the Tilt readings to judge my efficiency, but I do use them for ABV calculation. And obviously to answer, “have I hit FG?”