Fermentation went from 100 to zero -- LalBrew London Yeast

[RM-MN]

I do have hydrometer, i just forgot to take a sample. I did not use method of small concentrated boil with water top off. I did everything in 10 gallon kettle. Started with 6.5 gallons and ended around 5 gallons of wort. But your advice in that scenario makes sense to me.

There really is no need to take an OG sample on an extract beer. If you got 5 gallons or wort, the OG will be 1.046 or very close to it because that is how the recipe is made. It's only when you do all grain that the OG is important as you won't know how efficient your system is at converting starch to sugar and how efficiently you can recover the sugars.

 

[hotbeer]

If you have a decent way of getting a sample from the FV without opening the lid, then take a hydrometer or refractometer reading. Otherwise just be patient and let the FV sit for at least the full time recommended by the recipe.

Me... I'd wait for the beer in the FV to clear before I even considered taking a SG reading or bottling it. However when the beer does clear up, then it likely reached it's FG long before then.

 

[BrewnWKopperKat]

When brewing extract batches, measuring SG would confirm that the volume of wort is appropriate and that all the fermentable ingredients were added.

With full volume boils, this is easy to do.

With partial volume boils, there may not be a single approach for accurately measuring SG all possible partial volume approaches.