BrewBug, is a neat little toy that essentially has a "floating bob" that measures the temperature and specific gravity of the wort as it is fermenting, allowing for niceties like changing the temperature based on the specific gravity, and just really nice plots of the temperature and specific gravity.

Has anyone tried to DIY something like this before? I expect that the beer bug works by using a hollow bob with a temperature probe and measuring it's weight over time (with calibration). But I'm not sure where to get the "weight measuring" device: a linear actuator? A hook's law spring (changing weight to location) and then something to measure the position?

  • Two links, in the first sentence, to an item that would like to generate additional sales has generated a down vote from me. I hope this site doesn't turn into a way to promote items for sale.
    – Dale
    Nov 14 '16 at 23:54
  • 1
    @Dale: they were examples of what I was trying to diy. How do you think such a thing should be referenced? While I recognize that we don't want spam, I don't think this post is "spammy" in the least. Nov 16 '16 at 22:10
  • to meta: meta.homebrew.stackexchange.com/q/430/1643
    – Dale
    Nov 17 '16 at 1:49
  • Anyone tempted to click on the link and buy a Beer Bug, be forewarned: The Beer Bug is useless without the company's server, and that has not been functioning correctly for over 4 months now. I see that the support link has been disabled on the site, which does not bode well for the problem ever being fixed. Notice how the "nice plots" link goes to a blank page.
    – jalynn2
    Dec 22 '16 at 18:52

I'm using an online room temperature check system with raspberry pi and highcharts which i programmed for myself. It can be seen here

Basically raspberry pi sends temperature data to a db with a cronjob, and highcharts shows realtime data. But it is just for temperature not the gravity.

I followed this tutorial.


Using a raspberry Pi with a couple of temperature probes and statsd+graphite you could recreate the temperature vs time graphs. Using a BrewPi some of this work is done for you.

The more difficult bit to replicate would be the real time monitoring of the Specific Gravity that the BeerBug (formely BrewBug) offers. I have been having a think about this a looking through component catalogues and can't see anything immediately that would fit the bill.

I now really want to take one apart and see what components they are using.


The BrewBug, IIRC, uses a bulb type hydrometer. Measuring the weight is unnecessary as the bulb's position will indicate specific gravity. Also, no calibration is involved in this type of setup as hydrometers come pre-calibrated. You need only measure how high the hydrometer sits in the wort and adjust for temperature.

  • 4
    No, the BeerBug has a weight suspended by fishing line that is submerged in the wort. At the start of a batch, it must be tared, preferably by measuring the starting gravity with a standard hydrometer.
    – jalynn2
    Aug 21 '14 at 16:53

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