Specific Gravity Readings

[Isolec82]

Is it generally considered that the value of sg is uniform throughout the entire volume of the fermenting volume? I have 46l of German Pilsner fermenting in a Brewmaster and i think the tilt is caught up in the central cooling coils. I can bleed a small amount off from the nipple on the side, in order to use a digital refractometer - but will this be representative of the total mass.

 

[Larse]

Is it generally considered that the value of sg is uniform throughout the entire volume of the fermenting volume? I have 46l of German Pilsner fermenting in a Brewmaster and i think the tilt is caught up in the central cooling coils. I can bleed a small amount off from the nipple on the side, in order to use a digital refractometer - but will this be representative of the total mass.

Yeah, it would be uniform. Billions of yeast cells spread throughout the wort munching happily on the sugars. But also there is constant movement in the wort.

However if your hydrometer is resting on something, it may give false readings.

 

[Agentgonzo]

In most cases, yes, you can assume that.

However, if you are doing an extract brew, or any brew where you add stronger wort to the fermenter then top up with water, it's very unlikely that the wort will homogenise (even with a fair amount of stirring) when you measure the OG. it will homogenise over the course of fermentation but at the start it won't be. There have been quite a few threads where this has caught out extract brewers and their OG has been wildly off

 

[Larse]

In most cases, yes, you can assume that.

However, if you are doing an extract brew, or any brew where you add stronger wort to the fermenter then top up with water, it's very unlikely that the wort will homogenise (even with a fair amount of stirring) when you measure the OG. it will homogenise over the course of fermentation but at the start it won't be. There have been quite a few threads where this has caught out extract brewers and their OG has been wildly off

Would that not be just at the start before fermentation gets going? I read the OP to be enquiring about when fermentation is under way.

 

[Agentgonzo]

Would that not be just at the start before fermentation gets going? I read the OP to be enquiring about when fermentation is under way.

It wasn't clear to be whether the op was talking about the start, or after fermentation was underway