Missed FG by a mile

[Madhouse]

Hi All,

Am new to AG and this was my second brew, first one was a stout, aimed at 1.071, hit 1.066 but put this down to having to add water to the FV as I came up short. This time I was heading for 1.076, ended up with 1.056. It should still be a good beer, from a visual perspective it's my clearest yet (remembered the protofloc this time), I'm just a little perplexed at missing OG by a country mile.

Bit of background, I'm small-batch 5L FV, BIAB.

What I'd like your help on is why I missed the target gravity? Malt bill was straight-forward with 2.2kg pale and 0.1kg caramalt. Mash was 66 degrees for 65 mins, bit of fluctuation on the hob but it never got above 67 or below 62. Wasn't the most attentive on this one as had to put the kids to bed mid-mash, could it be that I didn't move the grains around enough?

Another thing I noticed was I lost a lot more water this time and needed to sparge to increase volumes. I give the bag a squeeze at mash out so believe I didn't lose any more to the grain than I needed to.

Any advice much appreciated!

 

[foxbat]

How did you come up with your OG estimates in the first place?

To get accurate estimates you have to take volume and gravity measurements pre-boil and post-boil then feed those back into your recipe software so it can use those figures to give you good estimates for the next time.

 

[Madhouse]

OG estimates were from the recipe. I then put in into Beersmith and increased the malt bill slightly to achieve target.

As my first brew was done in the same way I assumed this would be in the ballpark at least.

In this case pre-boil OG was 1.060, I know I should have probably added some sugar at this stage but I wasn’t sure how much to add so decided to settle for the lower abv.

OG went down as I lost more to the boil than expected so had to top up. Thinking about it that may not have helped me much either.

 

[Ghillie]

I'd bet the BH efficiency on the recipe was set to ~75% which may be a good bit more than what you're achieving.

What's more, scaling recipes isn't quite linear. You have scaled a 23L final volume recipe to 5L? Given it's 5L, you're boiling less wort and probably getting a much stronger boil - hence the alleged increased boil off. Totally normal.

Don't worry about the value of BH efficiency, but do worry about the consistency of that number. All that said, I do think with this being your second brew that you have plenty time to worry about that in brews to come. Try brewing a couple of basic SMaSH recipes (Single Malt and Single Hop) with the same amount of grain; then you'll be able to work out what ballpark SG for Xkg of grain will be. Once you've done that and have a rough idea, you can easily work out your estimated BH efficiency and then apply that to the likes of Beersmith.

So many factors impact BH efficiency, the biggest IMO being the grain crush size. This varies from supplier to supplier and even between batches from the same supplier! It will all fall into place eventually

 

[foxbat]

You should start setting up an equipment profile in Beersmith. You already have some figures to get started.

Enter the recipe in the Design page as you made it. Add the full volume of water you started with as an ingredient. Pick a BIAB equipment profile to get started.

Go to the mash page and enter the total water added as the mash volume for a single infusion mash. It will show zero for the sparge.

Go to the session page and enter pre and post boil gravities. Enter the volume you transferred to the fermenter as the measured batch size. You should now see a number calculated for "measured efficiency".

Now when you next enter a recipe make sure you start with that number as the efficiency number at the top of the design page.

You should also open up the equipment profile, enter your boiloff (difference between pre-boil and post boil volume after cooling) as soon as you can. Then save the profile under a custom name.

 

[Madhouse]

Thanks for the tips, I need to measure a bit more from my next brew I think.

Just looked at the malt in my last brew, 1600g. So that had less malt and a higher FG, definitely did something odd with this one.
Efficiency was set to 72% in Beersmith so a good chance that was incorrect, was 67% on my other recipe so maybe I'm at 60-something.

So thinking about stuff to do to improve next time:

• used a different pan this time, it'll be one I use going forward so would be best to work out boil off rate
• I need to measure how much water I lose to grain to properly calculate start volumes. Kettle doesn't have volume markings so need to create some kind of dipstick for volume.
• Have already set up a custom profile but it definitely needs a tweak or two
• more FG readings throughout the process - just found out you can adjust the reading according to the temp of the wort, that's good to know as I was cooling it and then taking a reading which takes time.

Aim from the above is to better work out my starting water volume so I'm not adding to the FV and work out efficiencies so I can have a better idea of what my overall malt weight should be.

Like you say, only second brew and still learning ........ don't think you ever stop where brewing's concerned

 

[Ghillie]

60 something is a good enough efficiency for any equipment setup, good work!

Some things that might help you:

-Stir the mash periodically, two or three times maybe.

-Squeeze the bag like there's no tomorrow

-Try a thinner mash.

-Don't use temperature correction for gravity readings. I've never had any success with those calculators, it's always off. Pull a sample in your trial jar and then stick it in the fridge or freezer. Take a reading at 20C.

Regarding your grain absorption, it's a pretty safe bet at 1L/kg. Beersmith is about 0.96L/kg by default. I've personally never had to change that and my sparge quantities never need adjusted.

 

[Madhouse]

Thanks.

I think stirring the mash is a key one - I didn’t do it this time for no other reason than I forgot.
Looking at the recipe again if I’d have got the same efficiency as the last brew I’d have missed target gravity the other way.

Already squeezing the bag for all it’s worth - must get some marigolds to defend against the heat.

Noted about the temp corrections, will stick with chilling the test volume.

I’ve totally overlooked grain absorption, between that and boil off I think I’ve undercalled my water requirement by 2 or 3 litres. That makes sense with all the top-ups I’ve had to do, athough if I’d got all I needed from the grains that shouldn’t have had too big an impact.

 

[Clint]

I'm still learning the process myself but feel I'm getting there regarding bhe,volumes etc as my brews are becoming smoother to conduct and consistent in results which I feel are important. I keep notes on every brew...
I also feel ready to move into water treatment...I've just ordered the basic test kits so really looking forward to this on my days off.

 

[Madhouse]

I keep notes on every brew...

Me too, I use OneNote which we also use at work so easy to update while everyone else thinks I'm working
Just need to take more notes and in more detail.

 

[Clint]

Very professional! You skiver...

 

[Madhouse]

Thank you all for the help, measured boil off last night and adjusted my equipment profile with that, set efficiency to 60% and grain loss to 1L/kg.
Will need further adjustments but I’m in a better position for my next brew.