Gravity too low; what have I done wrong?

[Twopan]

My first attempt at all grain using boil in the bag method. According to John Palmer's book this requires no sparge. Ordered the Malt Miller Leffe clone recipe, precisely scaled down to achieve a final volume of 17 litres (only have a 23L kettle). Used a large bag which fits around the rim. Mashed the c. 4Kg of mixed grain for 60 minutes at c. 68° ensuring plenty of room. Drained into the kettle without squeezing. Boiled for 60 minutes with hop pellets in bag and add 370ml of candy syrup in last 10 minutes. Gravity should have been 1.065 and I've only got 1.045! Advice gratefully received!

 

[Agentgonzo]

How much water did you use/collect? Can you post the full (scaled) recipe? Just chucking in the grain figures into the grainfather app and targeting 17l of beer, it came out (with my normal 80% efficiency) with an OG of 1.058.

Brew in a bag is typically a lower efficiency. If I drop the efficiency to 65%, then it comes out at 1.049 OG, which is fairly close to what you had.

I'm assuming you measured the gravity at 20°? Did you take the reading with a hydrometer or refractometer (the latter can be less accurate)? How vigorous was your boil (can you estimate how much water got boiled off)?

 

[foxy]

My first attempt at all grain using boil in the bag method. According to John Palmer's book this requires no sparge. Ordered the Malt Miller Leffe clone recipe, precisely scaled down to achieve a final volume of 17 litres (only have a 23L kettle). Used a large bag which fits around the rim. Mashed the c. 4Kg of mixed grain for 60 minutes at c. 68° ensuring plenty of room. Drained into the kettle without squeezing. Boiled for 60 minutes with hop pellets in bag and add 370ml of candy syrup in last 10 minutes. Gravity should have been 1.065 and I've only got 1.045! Advice gratefully received!

Did you end up with 17 litres? Was your grain bill for no sparge? Was your grain milled for a BIAB? Why didn't you squeeze the bag? The figures just don't add up for a 1,065 OG.

 

[Tanglefoot]

I BIAB no sparge, for comparison usually an 18L.batch of around 5.5% abv.
On average grain bill of 4.8kg and total starting water volume of 24L to allow for boil off losses.
Brewfather or similar will calculate rhis for you.
I use a 38L pan and with displacement of grain that comes pretty close to max capacity.
II always squeeze the bag and filter through a fresh grain bag into FV.
Also.mashimg at 68c is at higher end and could result in more unfermentable sugars.
Hope that helps.

 

[MrRook]

On my second BIAB I put the bag in a colander suspended over a small pot. I poured some water over it (sparge) three times and then gave a bit of a squeeze. I got 9 gravity points per pound compared to 7 gravity points in my first BIAB. that could easily make a 20 gravity point difference in a 10 lb grainbill.

 

[Twopan]

I BIAB no sparge, for comparison usually an 18L.batch of around 5.5% abv.
On average grain bill of 4.8kg and total starting water volume of 24L to allow for boil off losses.
Brewfather or similar will calculate rhis for you.
I use a 38L pan and with displacement of grain that comes pretty close to max capacity.
II always squeeze the bag and filter through a fresh grain bag into FV.
Also.mashimg at 68c is at higher end and could result in more unfermentable sugars.
Hope that helps.

Thanks so much. Learning a lot here.

 

[Twopan]

Did you end up with 17 litres? Was your grain bill for no sparge? Was your grain milled for a BIAB? Why didn't you squeeze the bag? The figures just don't add up for a 1,065 OG.

Yes I did end up with 17L after the boil - the calculations seemed spot on. The grain bill was 4,031g and crushed - not sure what difference a no-sparge grain bill makes - I just adjusted down the Malt Miller kit from23 litres. I didn't squeeze the bag simply because the John Palmer book said don't!!

 

[Twopan]

How much water did you use/collect? Can you post the full (scaled) recipe? Just chucking in the grain figures into the grainfather app and targeting 17l of beer, it came out (with my normal 80% efficiency) with an OG of 1.058.

Brew in a bag is typically a lower efficiency. If I drop the efficiency to 65%, then it comes out at 1.049 OG, which is fairly close to what you had.

I'm assuming you measured the gravity at 20°? Did you take the reading with a hydrometer or refractometer (the latter can be less accurate)? How vigorous was your boil (can you estimate how much water got boiled off)?

Thanks for your interest. No the temperature was still about 28 degrees when I took the 1.045 reading, using both a standard hydrometer and my ISpindel. I accept that this makes the true gravity nearer 1.047, but still way off target. I calculated that I needed 22 litres for the strike water, as the grain would absorb 2 litres. This was bang on and I had 20 litres remaining for the boil, which was a good rolling boil. That lost another three litres as predicted and I ended up with 17 litres in the FV. Should I have steeped the grains for longer than an hour perhaps, or squeezed the bag till the pips squeeked? Maybe as @Tanglefoot said the 68 degrees for the mash was a bit on the high side? I've attached my calculations for the 17 litre version

 

[Twopan]

On my second BIAB I put the bag in a colander suspended over a small pot. I poured some water over it (sparge) three times and then gave a bit of a squeeze. I got 9 gravity points per pound compared to 7 gravity points in my first BIAB. that could easily make a 20 gravity point difference in a 10 lb grainbill.

Good tip thanks

 

[Sandimas]

Welcome to all grain.

You have just discovered one of the things that makes AG brewing different to kit and extract brewing: with the latter, you brew to the recipe and hit your OG every time. With AG it very much depends on your mash efficiency, and that is different for every one of us, depending on your method, equipment and ingredients (grain crush). Recipes are sized for a specific mash efficiency (usually 75%), but many of us get lower than that e.g. I usually get 68% with BIAB. So your OG will be lower than the recipe, and you'd need extra grain to make up the difference and hit the OG.

After a few brews you should be able to work out your efficiency and work out the difference. Or just buy raw ingredients rather than kits, plug in your actual efficiency into brewing software, and then you should hit your target OG.

I have found sparging definately helps: I dunk sparge, twice, just to be sure.

 

[jof]

I would also guess no sparge.

You need to wash all the sugars from the grain.

Hint: if you taste the grain before the sparge, it will still be sweet. If you taste it after a successful sparge there will me much less sweetness.

You might want to look at dunk sparging for biab if you want to save some time over tricking water through the grain bed

 

[Twopan]

Welcome to all grain.

You have just discovered one of the things that makes AG brewing different to kit and extract brewing: with the latter, you brew to the recipe and hit your OG every time. With AG it very much depends on your mash efficiency, and that is different for every one of us, depending on your method, equipment and ingredients (grain crush). Recipes are sized for a specific mash efficiency (usually 75%), but many of us get lower than that e.g. I usually get 68% with BIAB. So your OG will be lower than the recipe, and you'd need extra grain to make up the difference and hit the OG.

After a few brews you should be able to work out your efficiency and work out the difference. Or just buy raw ingredients rather than kits, plug in your actual efficiency into brewing software, and then you should hit your target OG.

I have found sparging definately helps: I dunk sparge, twice, just to be sure.

Thanks. It clearly needs more research on my part. Next time I will work on efficiency and try a smaller batch again, 15L to make it easier to handle. Can you post a link to the software you mention please?

 

[Twopan]

I would also guess no sparge.

You need to wash all the sugars from the grain.

Hint: if you taste the grain before the sparge, it will still be sweet. If you taste it after a successful sparge there will me much less sweetness.

You might want to look at dunk sparging for biab if you want to save some time over tricking water through the grain bed

So does dunk sparging mean re submerge the bag, squeeze it, dunk it again etc?

 

[jof]

So does dunk sparging mean re submerge the bag, squeeze it, dunk it again etc?

I will describe what I have done. It's not necessarily correct but it does work, and I only do this when I am short on time.

I do a BIAB in a klarstein fullhorn (boiler)
Mash as normal using about 15l for a 25l batch of wort.
Drain wort into fermenting bin temporary.
Close tap!
Pour remaining 10l of strike water into mashing vessel.
Open the top of the bag & carefully stir, so water can get to all the grain, then close bag again.
Leave for 10 minutes & drain back into fermenting bin.

Remove grain bag to a large colander over saucepan to collect any remaining liquid

Pour content of fermentation bin back into boiler ready for the boil.

It's faster than a full sparge.
Its only a 2 vessel system, as I use the fermenting bucket as temporary storage.
But it does mean transferimg wort back up to the boiler at the end, so not without its faults.
That's why people talk about 3vessel system as a next stage on.

Hope that's useful to you.

 

[Twopan]

I will describe what I have done. It's not necessarily correct but it does work, and I only do this when I am short on time.

I do a BIAB in a klarstein fullhorn (boiler)
Mash as normal using about 15l for a 25l batch of wort.
Drain wort into fermenting bin temporary.
Close tap!
Pour remaining 10l of strike water into mashing vessel.
Open the top of the bag & carefully stir, so water can get to all the grain, then close bag again.
Leave for 10 minutes & drain back into fermenting bin.

Remove grain bag to a large colander over saucepan to collect any remaining liquid

Pour content of fermentation bin back into boiler ready for the boil.

It's faster than a full sparge.
Its only a 2 vessel system, as I use the fermenting bucket as temporary storage.
But it does mean transferimg wort back up to the boiler at the end, so not without its faults.
That's why people talk about 3vessel system as a next stage on.

Hope that's useful to you.

Great thanks. I think this is what a mate of mine does so I will talk through it with him as well.

 

[Sandimas]

. Can you post a link to the software you mention please?

Brewers Friend is one, but there are others out there.
https://www.brewersfriend.com/homebrew/recipe/calculator
You'll see that 75% is the default efficiency in Brewers Friend. Suggest plugging in your recipe and then adjusting the efficiency down until you reach the OG that you got, you can then tell what your efficiency figure was. Many of us got 55-70% on our early brews, so you can see it varies a lot. Please post what you got and we can go from there.

 

[Agentgonzo]

So does dunk sparging mean re submerge the bag, squeeze it, dunk it again etc?

Dunk sparging is dunking the bag in fresh (warm) water a few times, stirring out around and pulling it out (with or without squeezing), then adding that extra (now sugary) water to your wort.

As mentioned above, typical BIAB efficiency is 60-70%. If you mill (or get your grain milled if you don't have your own mill) finer, this efficiency will go up (and you'll get a higher OG with the same amount of grain). After a brew or two, you'll know what your efficiency is for your brews, and you can plan your recipes accordingly. It's just a number a the end of the day, so if it's lower, then you just throw some extra grain in to get the OG you need. For us homebrewers, the extra quid spent if you have a lower efficiency doesn't really matter much at all.

 

[Twopan]

Thanks @Sandimas . Well, that was an eye-opener! I did as you suggested and adjusted the efficiency %. Adjusting the hydrometer reading for the temperature my OG was c. 1.046. I plugged all the values in and adjusted the efficiency until 1.046 appeared, and it was 55% with an OG of 1.046, FG of 1.011 and 4.6% ABV. QED!! I obviously need to work better at getting the sugar out of the grain and upping the grain bill to achieve the desired result accepting that BIAB is less efficient. I attached the print out.

 

[Agentgonzo]

Given the boat has sailed for your mash on this brew, you can still do one or many of the following things.

• Add some sugar to your (presumably now fermenting) wort. This will increase the abv of the final beer, but not the body/flavour
• Add some boiled malt extract to your wort. This will increase both ABV and body/flavour
• Leave it as it is and have a lighter-than-planned beer.

 

[Twopan]

Thanks. Have already added the balance of the candy sugar syrup left in the bottle, which has added about 1 SG point. Shall I add say 500g of light DME and stir it in (with a sanitised spoon of course)?