"The BeerBugTM is a cloud connected digital hydrometer"

I already have a RaspberryPi that records the temperature of wort and stabilizes wort temperatures via a relay and a Fermwrap. The pain is that I have to take gravity readings, update my database, and manually turn up/down the heat based on the gravity.

I've put several hours into researching how to replicate this but have come up with nothing.

The only hint the company gives is the following:

The BeerBugTM's torpedo hangs down into your fermenting fluid and acts as a traditional hydrometer does. In short, this is a subject of the Archimedes principle - the force that is exerted on a body immersed in a fluid, is equal to the weight of the fluid that the body displaces.

  • "The pain is that I have to take gravity readings, update my database, and manually turn up/down the heat based on the gravity." — I'm not sure what you mean by this; what correlation do you think exists between gravity and temperature? What sort of database do you have? – jsled Apr 13 '15 at 15:34
  • @jsled This is for a diacetly rest mainly; Specifically for lagers according to the Brulosopher Quick Lager method, the temperature should be increased to 65*F once attenuation has hit 50%, and then dropped to lagering temperatures after FG has been hit. Right now I program it by time -- the database has a date record indicating when temperatures should increase, which I set to 7 days after pitching temperatures (which should roughly be when 50% attenuation occurs). The RPi checks the current date with the date in the DB and adjusts as necessary, but it would be better to use gravity than time – Matthew Moisen Apr 14 '15 at 1:04
  • @jsled But regarding your question, I currently take manual gravity tests and update the database with them so I can refer to it in the future. "On day 3 of this or that batch, what was the specific gravity?" type of questions. – Matthew Moisen Apr 14 '15 at 1:04

The Beerbug is simple on how it gets its SG readings. It uses a weighted buoy, or other contraption that sinks in the wort. then it reads how much it weighs, the lighter it is the thicker the wort. heavier it weighs, thinner or lower gravity of the wort......

If you look at these links, beerbug review 1 and 2 you can plainly see the weighted buoy attached with nylon? string.

it makes sense on why it is so cheap compared to actual sensors for reading density or pressure.

Picture for reference from http://www.brewbeerblog.com/2014/06/06/homebrewing-equipment-review-beer-bug-part-1/

enter image description here

You are probably going to need a load cell/strain guage, or some device to measure the weight of the buoy, you may be able to find a module on sparkfun or alibaba, or if you have more electrical know how build one, which i think i might, seeing how simple this is.


If I understand what you're trying to accomplish, you want a sensor that measures liquid density. Maybe something like this could be used: http://www.pvl.co.uk/hydrostatic-level-sensors.html

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