Apologies if this question has been asked before, I wasn't able to find anything specifically mentioning everything that happened on my brew day.... So, this is my second batch using BIAB, and intended on brewing up a ~8% porter (recipe below): Brew Method: BIAB Style Name: Robust Porter Boil Time: 60 min Batch Size: 1.5 gallons (fermentor volume) Boil Size: 2.5 gallons Boil Gravity: 1.056 Efficiency: 65% (brew house) STATS: Original Gravity: 1.093 Final Gravity: 1.031 ABV (standard): 8.13% IBU (tinseth): 41.5 SRM (morey): 50 FERMENTABLES: 4.06 lb - American - Pale 2-Row (67.2%) 0.34 lb - American - Carapils (Dextrine Malt) (5.6%) 0.16 lb - United Kingdom - Crystal 70L (2.6%) 0.34 lb - United Kingdom - Crystal 45L (5.6%) 0.34 lb - American - Dark Chocolate (5.6%) 0.34 lb - American - Roasted Barley (5.6%) 0.23 lb - Flaked Oats (3.8%) 0.23 lb - Flaked Barley (3.8%) HOPS: 0.23 oz - Columbus, Type: Pellet, AA: 15, Use: Boil for 60 min, IBU: 41.5 YEAST: Danstar Nottingham - 1 packet My pre-boil gravity came out to 1.048 (8 points below target), so I decided to extend the boil in hopes of concentrating the wort a bit more.... after boiling for 90 minutes, my OG came out to 1.130 lol!!! Did 30 minutes of extra boiling really bump up my OG by THIS much?? And should I consider diluting the fermenter volume with some sanitized water to get closer to the target OG? And if so, would this have any negative consequences on the final product? Thanks in advance for any and all help!
Now thinking on it further, perhaps my pre-boil gravity reading wasn't even accurate to begin with? (I didn't cool it down all the way to room temp, it was prob still at 80-90F when I used my hydrometer)
At hydrometer of 80-90 you would only be off by a little, not near the amount you report. There are temperature corrected calculators that you can find on homebrewing calculator websites, see what one of them say. Did you hit your target volume? This seems like too high of a boil off rate (27%?). Also, is your 65% calculated or assumed? Honestly I didn't build this in a recipe sheet, I am trusting your targets. As far as adding water, this is up to you. It is a standard procedure in extract brewing. Depending on your yeast, it is likely that they wouldn't be able to finish this job before the alcohol concentration got too high. I would strongly consider adding the water
I didn't see your actual post-boil volume anywhere. How much wort did you end up with after the boil? If it's less than 1.5 gallons, you should expect your gravity to be higher. I'd top up to 1.5 gallons with boiled and cooled water and call it a day. Also, I don't know your system, but that's a pretty pessimistic estimate for efficiency, IMO. I routinely end up with efficiencies in the low 80s with BiaB. Even brewing a beer that big, I'd start by targeting 70-75% efficiency in your recipes, unless you know for a fact that yours is lower.
Sorry, the 65% efficiency was only an initial estimate (my first biab efficiency was very poor, ~55%). My fermenter volume ended up closer to about 1.25 gallons after kettle trub losses. I did toss in an entire 11 gram packet of Nottingham, in hopes that it would be able to take it all the way down, though I did mash high at 159F to decrease attenuation a bit. And its honestly entirely possible that the hydrometer sample was even warmer than that, I honestly am not sure. I am definitely starting to consider adding in some sanitized water though - thanks!
My post boil volume was around 1.4-1.5 gallons, with a bit less in the fermenter after kettle trub loss. Yea, I only put in a 65% efficiency estimate because of how poor my first batch efficiency was, but I do think I seem to have improved upon that. Thanks for the tips guys! Gonna add in some cooled boiled water and call it a day
Well them, you have two options: Add ~.25 gallons of water to reach your target volume of 1.5 gallons. (You'll end up with stronger beer this way). Add enough water to reach your target gravity of 1.093. (You'll end up with more beer this way.) You can use this calculator to figure it all out: https://www.brewersfriend.com/dilution-and-boiloff-gravity-calculator/
Awesome!! Think I'll go the way of still trying to hit target gravity. Thank you!!! And sorry, I can only imagine how many times this has been asked over the years, but I just wanted to me sure haha Cheers!
I find it easier to take a pre boil reading than post boil (don't have to worry about sanitation). You do have to adjust for temperature though. I rarely bother with a post boil reading.
I will add that the water should be dechlorinated. If fermentation is done, it would be best practice to also deaerate too.
