Short Final Gravity

Australia & New Zealand Homebrewing Forum

Help Support Australia & New Zealand Homebrewing Forum:

MarkV

Member
Joined
12/7/15
Messages
12
Reaction score
2
Location
Sutherland Shire
G'Day brewers, I don't often write on on this forum but I have an issue that I would really appreciate some advice on. I've been brewing for several years now on my brew in a basket set up. I brew around 43 litre batches and most of my brews are between 1.050 and 1.070. I am using Brewfather for recipe building. Through the years I have used a plastic 60 L fermenter for a couple of years then progressed to a Fermemter king 60 L unitank and now for the first time I'm using a SS brewteck 50 L Cronical. I use the software in Brewfather to calculate my pitching rate. I've also used Beersmith and the yeast sites for calculations.
So the problem I always seem to have is my final finishing gravity is always short between 4-10 gravity points. I have a NEIPA fermenting at the moment the OG into fermenter was 1.068 and its has stopped after 9 days at 1.024. The target finishing gravity is 1.010. I used Lallemand Verdent IPA yeast and as said before I used the pitching calculator and did a starter from 2 packs. The target pitch was 729 billion cells and after my starter was ready 739 billion cells was pitched. I also Oxygenate with Oxygen. I started fermentation at 19C and ramped it up to 20C on day 5. The reading of 1.024 was taken on day 5 and again it was still1.024 on day 9. I'm not sure what else I can do? Any and all suggestions or possible solutions is much appreciated.
 

MHB

Well-Known Member
Joined
1/10/05
Messages
6,871
Reaction score
4,349
Location
Newcastle
The obvious first place to look is your mash temperature. If you mash too hot (we are only talking a couple of degrees) you will make more unfermentable dextrins and no matter how good your yeast pitch and preparation is it won’t ferment down as far as you want.

One easy way to check is to do a forced ferment test, basically take a small amount of wort and massively overpitch. Any decent dry yeast will do and many people just add about 1/4-1/2 a teaspoon of dry yeast to enough wort to take a reading (fill your hydrometer tube). That will get you down to your FG in 24-48 hours. If you fall short again it’s probably your mash temp.
You could even do a force test on some beer that you think has finished, just let it warm up before adding the yeast.

Every brewer should have one good quality lab thermometer that they use to calibrate everything else. You can’t really trust electronic or analogue thermometers without regular calibration.
Mark
 

MarkV

Member
Joined
12/7/15
Messages
12
Reaction score
2
Location
Sutherland Shire
The obvious first place to look is your mash temperature. If you mash too hot (we are only talking a couple of degrees) you will make more unfermentable dextrins and no matter how good your yeast pitch and preparation is it won’t ferment down as far as you want.

One easy way to check is to do a forced ferment test, basically take a small amount of wort and massively overpitch. Any decent dry yeast will do and many people just add about 1/4-1/2 a teaspoon of dry yeast to enough wort to take a reading (fill your hydrometer tube). That will get you down to your FG in 24-48 hours. If you fall short again it’s probably your mash temp.
You could even do a force test on some beer that you think has finished, just let it warm up before adding the yeast.

Every brewer should have one good quality lab thermometer that they use to calibrate everything else. You can’t really trust electronic or analogue thermometers without regular calibration.
Mark
The obvious first place to look is your mash temperature. If you mash too hot (we are only talking a couple of degrees) you will make more unfermentable dextrins and no matter how good your yeast pitch and preparation is it won’t ferment down as far as you want.

One easy way to check is to do a forced ferment test, basically take a small amount of wort and massively overpitch. Any decent dry yeast will do and many people just add about 1/4-1/2 a teaspoon of dry yeast to enough wort to take a reading (fill your hydrometer tube). That will get you down to your FG in 24-48 hours. If you fall short again it’s probably your mash temp.
You could even do a force test on some beer that you think has finished, just let it warm up before adding the yeast.

Every brewer should have one good quality lab thermometer that they use to calibrate everything else. You can’t really trust electronic or analogue thermometers without regular calibration.
Mark
Thanks MHB, I mashed this last brew at 67c which is what this recipe required the mash to be. My Element is controlled by a PID and is always within one degree of my thermopen. It is very possible that they are both out of calibration. I will need to investigate this further. To be honest 67c is a little higher than I normally mash at, which is usually 65-66c. And even then I’m 4-6 points short of my target. I do like the idea of testing with yeast as you said. Nevertheless I do feel like there may be some other variable contributing to my problem.
 

MHB

Well-Known Member
Joined
1/10/05
Messages
6,871
Reaction score
4,349
Location
Newcastle
Sure there are other possible causes, mash temp is just the most common and easy to diagnose.
If you are confidant of your temperatures post a bit more information on your equipment, ingredients and processes and we can look for other explanations.
Just be very careful calibrating your thermo pen and PID, I really do recommend a good glass lab thermometer; they tend to be right or broken and nowhere in-between. My local stocks a very good one for about $15 it’s French made, have seen some crap thermometers that were 20oC out.
Mark
 

MarkV

Member
Joined
12/7/15
Messages
12
Reaction score
2
Location
Sutherland Shire
Sure there are other possible causes, mash temp is just the most common and easy to diagnose.
If you are confidant of your temperatures post a bit more information on your equipment, ingredients and processes and we can look for other explanations.
Just be very careful calibrating your thermo pen and PID, I really do recommend a good glass lab thermometer; they tend to be right or broken and nowhere in-between. My local stocks a very good one for about $15 it’s French made, have seen some crap thermometers that were 20oC out.
Mark
Okay thanks, I’ll post some more information. This pretty much is the norm for my brews no matter what I brew, so I need to figure this out. Although this last brew in the new SS cronical is one of the worst.
Mark v
 

MarkV

Member
Joined
12/7/15
Messages
12
Reaction score
2
Location
Sutherland Shire
Sure there are other possible causes, mash temp is just the most common and easy to diagnose.
If you are confidant of your temperatures post a bit more information on your equipment, ingredients and processes and we can look for other explanations.
Just be very careful calibrating your thermo pen and PID, I really do recommend a good glass lab thermometer; they tend to be right or broken and nowhere in-between. My local stocks a very good one for about $15 it’s French made, have seen some crap thermometers that were 20oC out.
Mark
h
Sure there are other possible causes, mash temp is just the most common and easy to diagnose.
If you are confidant of your temperatures post a bit more information on your equipment, ingredients and processes and we can look for other explanations.
Just be very careful calibrating your thermo pen and PID, I really do recommend a good glass lab thermometer; they tend to be right or broken and nowhere in-between. My local stocks a very good one for about $15 it’s French made, have seen some crap thermometers that were 20oC out.
Mark
0F462D75-AFD3-4899-B174-5D3EB13EC836.png

Here is the recipe.
As stated earlier I brew in a basket in a 100litre kettle, mash for 60min then mash out. I then rinse the grains to achieve the required volume and starting gravity. Boil for 60min. Chill, add oxygen then pitch yeast.
 

MHB

Well-Known Member
Joined
1/10/05
Messages
6,871
Reaction score
4,349
Location
Newcastle
Nice amount of information to work through, if you did exactly what was in the recipe I wouldn’t expect any problems. Certainly not the under attenuation you are experiencing.
The next most obvious places to look would have been Ca pH L:G... It appears that you have those all pretty well covered.

I'm going to stick with mash temp being the most likely until you have checked it more carefully. I would put in your normal amount of strike water, heat to your calculated strike temperature, stir thoroughly and measure the temperature with something you can trust.
It could be as simple as sensor location and the liquor being a lot hotter above the sensor than you think.
When you mash in you could be killing off a lot of your Beta Amylase.
Try that and see what you get.

A couple of other places to look
Your apparent attenuation (AA) is around 76.5%, I don’t know this yeast all that well but a quick look at the spec sheet says medium to high attenuation so I would expect that to be OK. Getting down to1.010 requires you’re AA to be 85% which might be a bit harder. A touch of a good yeast nutrient may help if you are near the limits for the yeast.

The other very real possibility that comes to mind is how you are managing your yeast starter, some procedures give you a lot more yeast that isn’t in very good condition (low vitality) I would be tempted to spend the extra money and pitch more dry yeast directly or if you have the option split a brew pitch half with dry yeast at the recommended rate and the other half with propagated yeast and see if there is any difference.
Mark

Edit
Pull a glass of beer and do a force test on it, that should tell you if its the mash/strike temp!
M
 

An Ankoù

Well-Known Member
Joined
4/2/19
Messages
147
Reaction score
67
Location
Brittany, France
Sure there are other possible causes, mash temp is just the most common and easy to diagnose.
If you are confidant of your temperatures post a bit more information on your equipment, ingredients and processes and we can look for other explanations.
Just be very careful calibrating your thermo pen and PID, I really do recommend a good glass lab thermometer; they tend to be right or broken and nowhere in-between. My local stocks a very good one for about $15 it’s French made, have seen some crap thermometers that were 20oC out.
Mark
Same thing goes for the hydrometer. The calibration temperature will be marked somewhere on the glass tube check it in plain water at that temperature and it should read 1000, if not adjust your beer reading up or down by the difference. I really don't get the point of refractometers and bluetooth things that float in your beer, they're just toys. You can even calibrate your barbecue thermometer against a cheap laboratory thermometer.
 

An Ankoù

Well-Known Member
Joined
4/2/19
Messages
147
Reaction score
67
Location
Brittany, France
Its not fermenting under pressure so no co2 in the sample
That's not right @MarkV . Fermenting beer at normal pressure contains CO2 otherwise your beer wouldn't be fizzy. True, the higher the pressure the more gas dissolved, but it's still a good idea to either degas the sample or spin the hydrometer to set attached gas bubbles free.
 

MarkV

Member
Joined
12/7/15
Messages
12
Reaction score
2
Location
Sutherland Shire
Are degassing your samples before taking the
That's not right @MarkV . Fermenting beer at normal pressure contains CO2 otherwise your beer wouldn't be fizzy. True, the higher the pressure the more gas dissolved, but it's still a good idea to either degas the sample or spin the hydrometer to set attached gas bubbles free.
Okay i see what your saying. My normal practice is to spine the hydrometer a few times but also leaving it sit in the sample for about an hour and repeat the test. So I guess I’ve have been degassing.
 

rizrah

Well-Known Member
Joined
11/4/10
Messages
63
Reaction score
12
Location
SE Melb
Okay i see what your saying. My normal practice is to spine the hydrometer a few times but also leaving it sit in the sample for about an hour and repeat the test. So I guess I’ve have been degassing.
fill the hyrdometer tube 3/4 of the way up, cover the top and shake a few times, you will hear a "pfft" of co2, when you lift your hand off the top, thats co2 in solution. I usually take my sample in a little jug, then pour it back and forth a few times between the jug and hydrometer tube to fully degas the sample.
 
Top