How do people with conical (or other sealed) fermenters avoid sucking liquid from the airlock into the vessel when they take samples or remove trub through the bottom valve? Do they just remove a plug from the top and let air in to replace the liquid volume that's been lost? If so, doesn't that cause a contamination/oxidation risk?

2 Answers 2


There is a trick to pulling a small sample or drawing yeast.

Use a 1" blow off tube of ample length to reach the bottom of a bubbler jar on the floor.

The volume in the tube is enough to draw a small sample, as you draw the sample you will see the sanitizer suck up in the tube, don't let it crest the arch and you're ok.

For a large draw you can use a sanitary air filter in place of the airlock to prevent contamination, minimal air is ok, but you can also attach c02 to replace the lost volume if worried about o2 exposure.

  • So, if I understand you correctly, if you have a bubbler attached, you have to take it out, and replace it with a blow-off tube -- is that right? Jan 22, 2016 at 12:28
  • @GilesThomas if you're using a 3 piece or S type airlock, best solution is to use a sanitary air filter. Jan 22, 2016 at 13:33
  • As a replacement to the original airlock throughout the fermentation process? Or just while sampling? Jan 22, 2016 at 18:22
  • @GilesThomas just while sampling Jan 22, 2016 at 18:23

An s-type airlock allows air in, but the liquid remains in the airlock rather than getting sucked in

  • While they do function like this they do not sanitize or filter the air entering the fermentor, though you could apply a filter or co2 to their outlet. Jan 23, 2016 at 21:11

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.