I attempted to make a Brewers Best American Pale Ale extract kit, OG was to be between 1.051-1.055 but it ended up as 1.039, after looking into why this was off so much, I see that I topped the water off to the top notch of the 6.5 gallon big mouth bubbler, indicating that this might be 6 gallons of brew and not 5.
The estimated FG was to be 5.0-5.5, but it looks like it’s going to be around 3.8%, this brings several questions…
Is there anything that can be done to correct this?
Will there be enough head space to ferment? It looks like there should be.
What’s the worst case/best case scenario?
Best case is a 3.8% session beer with a little less flavor than the original recipe if the 1.039 OG was an accurate reading. Sometimes an OG reading when top off water is added is not accurate because the wort is not evenly mixed.
Fixes can often lead to more problems. You could siphon off a gallon of the wort and heat it with about a pound and a half of DME. This may raise the SG by about 11 points. This may also drastically change the flavor profile of the recipe.
I would leave it as it is and install a blow off tube on the fermentor.
I would say to just let it ride and live with the 3.8% beer that you get out at the end. Those can be very nice, and it will give you something to drink on while you make the next batch.
Monkeying with it, as state above, can just lead to worse problems in many cases. It might be a bit too bitter though, hard to say.