Would gravity readings differ from top to bottom?

[silvervan83]

I had a buddy over the other night and was explaining the process to him. We were talking about knowing when fermentation was done and I explained the hydrometer and taking readings. He asked me something that kind of got me thinking...

Would a reading from the top of your vessel be different than one from the bottom?
I'm thinking that it would make sense that a reading from the top would show fewer points because more alcohol would be at the top. I know it wouldn't be that much of a difference for 5 or 10 gallons but what about a 1500 gallon conical at a local brewery?

 

[SumnerH]

I had a buddy over the other night and was explaining the process to him. We were talking about knowing when fermentation was done and I explained the hydrometer and taking readings. He asked me something that kind of got me thinking...

Would a reading from the top of your vessel be different than one from the bottom?
I'm thinking that it would make sense that a reading from the top would show fewer points because more alcohol would be at the top. I know it wouldn't be that much of a difference for 5 or 10 gallons but what about a 1500 gallon conical at a local brewery?

Normally, no. The action of fermentation stirs the beer pretty violently, and it would have to sit still for a _long_ time (longer than a brewery is going to let it sit with no turnover) to layer out like that.

The one common exception is in partial-boil brewing (which is almost always extract), where it's tough to mix the top-off water and wort thoroughly so you will get some striation.