DME to increase OG?

Rogermort · May 1, 2017

After two years brewing AG almost trouble free (but not too fussed about hitting specific target points), the past two weeks have been a nightmare.
Missing pre-boil gravity I used the Beersmith 'Adjust gravity tool' to calculate how much DME to add to the kettle.
To use today's as an example, looking to raise 34 litres from 1.024 to 1.038. BeerSmith tells me to add around 1.3 kg of DME.
Post boil gravity was intended to be around 1.045.
It came in at 1.058!!!!

What am I doing wrong?

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Pawlo7671 · May 1, 2017

I would add the DME after the boil and slowly adjust your OG

Rogermort · May 1, 2017

Just to clarify, BeerSmith suggests adding the DME 'undiluted'. Should it not be added pre-boil to the kettle then?

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Pawlo7671 · May 1, 2017

Rogermort said:
Just to clarify, BeerSmith suggests adding the DME 'undiluted'. Should it not be added pre-boil to the kettle then?

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I think that beersmith is referring to extract brewing, if you have enough sugars from your grains for proper hop isomerization then adding a bit of DME post boil to up your OG is fine

MrRook · May 1, 2017

Rogermort said:
After two years brewing AG almost trouble free (but not too fussed about hitting specific target points), the past two weeks have been a nightmare.
Missing pre-boil gravity I used the Beersmith 'Adjust gravity tool' to calculate how much DME to add to the kettle.
To use today's as an example, looking to raise 34 litres from 1.024 to 1.038. BeerSmith tells me to add around 1.3 kg of DME.
Post boil gravity was intended to be around 1.045.
It came in at 1.058!!!!

What am I doing wrong?

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How thoroughly did you mix the extracts in? Sometimes false readings can occur when extracts are not completely mixed in. Or was the 1.058 after boiling?

Rogermort · May 1, 2017

The 1.058 was after boiling.

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MrN · May 1, 2017

Was your boil off greater than expected? Have you checked that the gravity point contribution is set correctly for dme in beersmith?

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Rogermort · May 2, 2017

Boil off was marginally lower than expected. As to the second question, how would I check that? The calculator is in BeerSmith 2 mobile and I think it's meant to be a rule of thumb calculator. It only mentions DME, LME and water.

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serum · May 2, 2017

There's no harm adding it to the kettle pre-boil but it's hard to know what you'll end up with if you do it that way. Are you sure you measured the pre boil correctly and took temperature into account?

It took me quite a while to tune in my old setup so the pre and post boil would be accurate. I've now changed my equipment and find that I'm miles out on my pre boil but always hit post boil bang on.

You don't know exactly what your post boil gravity will be until you get to the end and get it cooled but then you've got to get the DME to dissolve.

MrN · May 2, 2017

Rogermort said:
Boil off was marginally lower than expected. As to the second question, how would I check that? The calculator is in BeerSmith 2 mobile and I think it's meant to be a rule of thumb calculator. It only mentions DME, LME and water.

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Oh right I don't think you can change that in the adjust gravity calculator. Even if it was wrong I don't think it'd be off by that much...

Was 34 litres the volume at the point you added the dme or the expected end volume? I think a slight overshoot in gravity pre boil can become a larger one post boil.

Rogermort · May 2, 2017

serum said:
Are you sure you measured the pre boil correctly and took temperature into account?

As sure as I can be. I cooled the sample to 20C before taking the reading and the reading came in at 1.024 (I was aiming for 1.038). I think I know what that problem was caused by though. I was so intent on slowing the sparge rate that I think my sparge water was getting to the grain bed having sat in pipework and pump for too long. Basically, too cool.
I'm now planning switching to a rotating sparge arm and gravity feeding it direct from the tap on the HLT. My theory is that if the only tap I have to worry about on the HLT side of the grain is the one from the vessel (rather than the one on the outflow of the pump) the rate should be easier to run slowly while maintaining temperature.

What I'm getting confused by is that having realised I haven't hit the numbers in the collected wort (cooled sample) sitting in the boil kettle, I asked BeerSmith for the addition thinking it needed to be added pre-boil and I'm ending up with a very strong wort post-boil!

Rogermort · May 2, 2017

MrN said:
Was 34 litres the volume at the point you added the dme or the expected end volume? I think a slight overshoot in gravity pre boil can become a larger one post boil.

There were 34 litres of 1.024 (sample measured at 20C) wort in the kettle when I added 850 grams of DME. I then boiled it down to around 28 litres and ended up with 1.059 (sample measured at 20C).

It was a nightmare session to be honest. The boil kettle packed up (plug burned out) mid boil and I had to quickly transfer everything to the HLT to recommence the boil! The garage cum brewery looked like a war zone by the time I'd finished!

MrN · May 2, 2017

Did you measure the gravity after adding the dme? Assuming you measured your volumes correctly you must have misread the gravity reading or added too much dme. I use this calculator and have always found it accurate - https://www.brewersfriend.com/dilution-and-boiloff-gravity-calculator/

It says that, based on your volumes, to end up with 1.058 you'd have needed to have started with 1.048. Could you have been 10 points off when reading your hydrometer the first time?

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The Idiot · May 2, 2017

To be honest, in too many decades of brewing I've never bothered with pre-boil gravities. Assuming all things to be equal, you tried to raise the pre-boil gravity from 1.024 to 1.038 (an increase of 0.014) to end up with an OG of 1.045 but instead hit 1.058 (an increase of 0.013).

Now, I'm not a maths person, but my seat-of-the-pants brewing figures suggest that had you left it alone you'd have hit your target (or maybe missed it by a gnat's privates).

I know some people love brewing software (I do write all my recipes in BeerSmith, but double check everything on my own records), and thrive on figures, but beer was brewed for centuries without such things, and generally over-focusing on numbers can lead you astray.

serum · May 2, 2017

For a starter where you want a litre at 1.040 I use about 100g of DME so doing a rough calculation if you divide that by 40 and multiply by 14 which is the number of points per litre you want that'd work out at 35g per litre of wort to raise by that much. Multiply that by 34 and you get 1.19kg. This is a very rough calculation but my guess would be similar to beersmith's.

I think either the boil off was really high or the initial reading was wrong.

What was the final volume?

Fil · May 2, 2017

is your hlt under temp control? if so how long was it stood at temp waiting, there is a feature of temp controlled hlt's that results in the target temp being maintained at the point of the temperature probe, BUT the liqour can 'stratify' into layers which are cooler below the temp probe and warmer above.. this can be easily rectified by giving the hlt liquor a damn good stir before sparging, some lazier brewers have been known to add recirculation pumps or motorised paddles to keep the liquor moving and ensuring a consistent temperature throughout the liquor..

when i noticed this the liquor i was initially drawing off for spargeing was a good 10C lower than the target temp!! My hlt had been stood @ temp for some time tho...

if your hlt was full to capacity and your sparge left a significant volume behind this may explain a less than spectacular efficiency leaving sugars behind in the grain due to too cool a sparge??

Rogermort · May 2, 2017

MrN said:
Did you measure the gravity after adding the dme? Assuming you measured your volumes correctly you must have misread the gravity reading or added too much dme. I use this calculator and have always found it accurate - https://www.brewersfriend.com/dilution-and-boiloff-gravity-calculator/

It says that, based on your volumes, to end up with 1.058 you'd have needed to have started with 1.048. Could you have been 10 points off when reading your hydrometer the first time?

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I didn't re-do the reading after adding the DME (but pre boil) and I'm pretty sure I didn't misread the hydrometer. Certainly not by more than a point or so when deciding where the meniscus read.
I always used to take iPhone pics of the hydrometer readings so that I could zoom in on the pic for an enlarged image but while I didn't do it yesterday, I'm confident the 1.024 that caused me to reach for the DME was an accurate reading. I cooled the sample to 20C too (which my hydrometer claims to be calibrated to).

Rogermort · May 2, 2017

The Idiot said:
To be honest, in too many decades of brewing I've never bothered with pre-boil gravities. Assuming all things to be equal, you tried to raise the pre-boil gravity from 1.024 to 1.038 (an increase of 0.014) to end up with an OG of 1.045 but instead hit 1.058 (an increase of 0.013).

Now, I'm not a maths person, but my seat-of-the-pants brewing figures suggest that had you left it alone you'd have hit your target (or maybe missed it by a gnat's privates).

I know some people love brewing software (I do write all my recipes in BeerSmith, but double check everything on my own records), and thrive on figures, but beer was brewed for centuries without such things, and generally over-focusing on numbers can lead you astray.

My last two brews have had similar problems and, by coincidence, my last two brews have seen me shift towards trying to hit the numbers bang on. Trying to brew a 4% beer rather than a 5% beer. 'Led astray' is probably an accurate summary of where I've been.

MrN · May 2, 2017

I guess just chalk it up to a misstep somewhere and don't worry about it unless it becomes a recurring issue, at which point it'll hopefully become easier to diagnose!

This is why I like to note down as many things as possible during my brew day - the more info you have, the easier it is to pin point issues!

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Rogermort · May 2, 2017

serum said:
For a starter where you want a litre at 1.040 I use about 100g of DME so doing a rough calculation if you divide that by 40 and multiply by 14 which is the number of points per litre you want that'd work out at 35g per litre of wort to raise by that much. Multiply that by 34 and you get 1.19kg. This is a very rough calculation but my guess would be similar to beersmith's.

I think either the boil off was really high or the initial reading was wrong.

What was the final volume?

Estimated post-boil volume was a shade over 29 litres with a batch volume to go into the fermenter of 25 litres (inc a 1.25 litre starter). I actually put around 26 litres into the fermenter (bear in mind I'd switched boil kettles mid-process!) and because of the high reading I drained off the DME from the starter before pitching. I figured there was already enough concentrated malt in there!

DME to increase OG?

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