Final Gravity Issues

[yukonhijack]

So I have been brewing for a few years, and have had this issue from time to time. Today is a good example of it.

I brewed an AG DF 60 clone using the recipe I found here (its awesome BTW, as I have brewed it like 4 times now). I hit my pre-boil gravity dead on, though my pre-boil volume was about .25 gallons higher than the recipe called for. However, after a 60ish minute boil, my post boil gravity was only 1.061 and it should have been 1.067. Should I have boiled a bit longer given the slightly extra wort volume pre-boil? I have not figured out my boil off volumes yet (should do that soon), but I think I am close in BeerSmith.

Any thoughts?

Greg

 

[feinbera]

If your pre-boil gravity is correct, your post-boil gravity is off, and you're not measuring your boil-off, probably you're boiling off less than you expect. There are more exotic possibilities – poor wort mixing leading to bad readings, failure to correct hydrometer readings for temperature, malicious aliens beaming fermentables out of your kettle, etc. But I'd verify that the thing I'm not measuring actually is what I think it is before I start questioning the measurements I am taking.

 

[MattyIce]

Extending the boil is something you should plan for before you begin the boil (as you recognized the volume was high at that time). This is so that you can boil the wort down to the proper pre-boil volume before you start your hop additions. For example, I might end up with 7.5 gallons of wort pre-boil. Knowing my system, I'll need to boil for a total of 90 minutes to end up with 5 gallons in the fermentor. This means I would boil for 30 minutes before I made my first bittering addition in order to stick with the recipe.

All part of getting to know your system. Figuring your boil-off rate is pretty important, especially with the high-gravity brews IMO.