Hydrometer reading

[Adrien]

Hello again

Anyone mind telling me how on earth I take a hydrometer reading from my demijohn cider fermentation without introducing any o2?
The only way I can get in is to remove the airlock thus letting air in.

 

[Yooper]

Remove the airlock, remove the sample, replace the airlock. Make sure the demijohn is always filled to near the top or middle of the neck. That's pretty much all there is to it.

 

[Epond83]

I have a turkey baster that to took the top off and use as a thief.