Gravity Issue / Questions

I brewed a batch of Denny's Wry IPA and bottled last night. Denny's fav yeast was used. Stayed in primary for 21 days.
Here's the numbers:
Pre-Boil OG: 1.055
Post Boil OG: 1.082
Recipe shows an OG of 1.078 and a FG of 1.019.
FG ended up at 1.031.

My OG was 4 points higher than what it should have been.
Reading through my notes, fermentation was pretty vigorous for 4 days then started to calm down.

I checked the gravity two days ago and it was at 1.031.

I also brewed a Sweetwater clone on 11/13 using US-05 and the post boil OG was 1.075- it should have been 1.062.

Why are my brews not fermenting out completely?
Could the cause be under pitching yeast?
Will there be any noticeable taste difference since my FG numbers are high?

I guess I should have added water to bring down the OG but at the time didn't think about it.

I use home brew dads or Mr Malty calculators to obtain the required amount to pitch and I usually add a little more to be on the same side. I added an additional .4 oz of Denny's as the yeast was harvested from a previous batch.

1. Oxygenation - Higher OG worts need a lot of O2 for proper yeast heath.
2. Mash temp - How accurately did you control this?
3. Thermometer accuracy - Have you verified the accuracy of your thermometer at mash temps?
4. Pitch rate - Higher OG worts could benefit from higher than usual pitch rates.

Also, increasing the ferm temp a few degrees near the end of active fermentation will help the yeast finish.

LLBeanJ said:

1. Oxygenation - Higher OG worts need a lot of O2 for proper yeast heath.
2. Mash temp - How accurately did you control this?
3. Thermometer accuracy - Have you verified the accuracy of your thermometer at mash temps?
4. Pitch rate - Higher OG worts could benefit from higher than usual pitch rates.

Also, increasing the ferm temp a few degrees near the end if active fermentation will help the yeast finish.

Click to expand...

#1>> I don't have a oxygen setup so all I did was shake the crap out of the bucket prior to pitching. I supposed I need to get a pump and a oxygen stone.
#2>> Mash temps stayed within 2 degrees the entire mash time.
#3>> My thermometer is calibrated. I'll re-check the calibration today to make sure it is accurate.
#4>> When i measured the post boil OG i increased the pitch amount to compensate.

When I entered the fermentables into brewers friend, the original OG was 1.091 so I cut back on the grains to get to 1.078.

How are you measuring gravity? If with a refractometer, you need to use a calculator to correct the reading during and after fermentation.

Reading your notes about OG, I would question a pre-boil reading of 1.055 and post boil 1.082. For my system a 1 hour boil adds around 10 points of gravity from pre-boil. How long are you boiling? Are you stirring the wort pre-boil to make sure it's mixed well before taking a reading?

oujens said:

How are you measuring gravity? If with a refractometer, you need to use a calculator to correct the reading during and after fermentation.

Reading your notes about OG, I would question a pre-boil reading of 1.055 and post boil 1.082. For my system a 1 hour boil adds around 10 points of gravity from pre-boil. How long are you boiling? Are you stirring the wort pre-boil to make sure it's mixed well before taking a reading?

Click to expand...

I'm measuring using a hydrometer, which is calibrated.
I boil for 60 minutes and i stir before I take a sample. I let the sample cool to 60 degrees or close to that then use a calculator for temp adjustment.

I thought the pre boil OG was high for my last two brew's. It's frustrating that I cannot determine the cause so i can fix it.

As a note, this is only my 4th time checking gravity. My first 4-5 brew's I didnt worry about it. Then bought a hydrometer, used it one time and cracked when spinning in the tube. So I have used the same hydrometer for the last three brews.

I went back to my notes for my third to last batch. The Preboil OG was 1.046 and the post boil OG was 1.066. Not sure what's happening here to cause the increased OG/FG.

I would like to get this fixed before this coming Wednesday which is my next brew day.

If I read this correctly, it sounds like your hydrometer is cracked. That is probably why you are getting some weird readings. If you haven't replaced it, I would start there. Keep taking notes and dial in your efficiency. It will help you hit your numbers consistently.

oujens said:

If I read this correctly, it sounds like your hydrometer is cracked. That is probably why you are getting some weird readings. If you haven't replaced it, I would start there. Keep taking notes and dial in your efficiency. It will help you hit your numbers consistently.

Click to expand...

The hydrometer I have now is new- my first one cracked.

How did you control fermentation temperature?

I have had yeasts crap out mainly due to two factors. Firstly, improper oxygenation. For example one time I left the o2 regulator on after oxygenating last batch and was out of o2 unexpectedly so I attempted to oxygenate by shaking.

Secondly, bad temperature control. I recently moved to a summerless climate (England) and wasn't used to having to keep my brews heated in July. I had 4 beers finish at 1.020 and it didn't stop until I switched to a two stage controller and added heat. Once I did that, the beers finished where they were supposed to.

I would recommend starting with a smaller OG beer. I am not surprised that a big beer ends up at 1.031. Once the yeast produces more alcohol than it can tolerate, it is going to stop. I don't know about Denny's but this would be especially true of a lower attenuating yeast. Try starting with a lower OG beer and a known high attenuating yeast.

Are you tracking how much water is being boiled off? Are you adjusting your preboil OG to account for smaller volume postboil? If you miss your numbers on the high side, I would top off.

What was your process for pitching the yeast? Did you build a starter beforehand?

Here's info on his yeast:

YEAST STRAIN: 1450 | Denny's Favorite 50

Back to Yeast Strain List

This terrific all-round yeast can be used for almost any beer style, and is a mainstay of one of our local homebrewers, Mr. Denny Conn. It is unique in that it produces a big mouthfeel and accentuates the malt, caramel, or fruit character of a beer without being sweet or under-attenuated.

Origin:
Flocculation: Low
Attenuation: 74-76%
Temperature Range: 60-70F 15-21C
Alcohol Tolerance: ABV 10%

badmajon said:

How did you control fermentation temperature?

I have had yeasts crap out mainly due to two factors. Firstly, improper oxygenation. For example one time I left the o2 regulator on after oxygenating last batch and was out of o2 unexpectedly so I attempted to oxygenate by shaking.

Secondly, bad temperature control. I recently moved to a summerless climate (England) and wasn't used to having to keep my brews heated in July. I had 4 beers finish at 1.020 and it didn't stop until I switched to a two stage controller and added heat. Once I did that, the beers finished where they were supposed to.

Click to expand...

I have a fermentation chamber- beer temp is 64 degrees.

Oxygenation could be the culprit as i only shake the carboy. I'll get a stone and a pump and try that but figured shaking the crap out of the carboy would be sufficient since i do it for 2-3 minutes before adding my yeast.

Aristotelian said:

I would recommend starting with a smaller OG beer. I am not surprised that a big beer ends up at 1.031. Once the yeast produces more alcohol than it can tolerate, it is going to stop. I don't know about Denny's but this would be especially true of a lower attenuating yeast. Try starting with a lower OG beer and a known high attenuating yeast.

Are you tracking how much water is being boiled off? Are you adjusting your preboil OG to account for smaller volume postboil? If you miss your numbers on the high side, I would top off.

What was your process for pitching the yeast? Did you build a starter beforehand?

Click to expand...

My boil off rate is approx 1 gal/hour and it's been that way for each brew that i've done. I guess what I'll do next time is top off with a bit of water to lower the OG.

In the case of Denny's Rye IPA, the Denny's fav I used was harvested from a previous batch. It was about a month in the fridge. I did make a 1L starter and pitched 5 oz of slurry. Called for 140 b cells and I assume 1oz = 30 b cells.
I dropped the wort temp to 68 then pitched the yeast which was at 63 degrees.

I saw that you mentioned that mash temp was within 1-2 degrees for the entire mash...if you don't mind, what was the mash temp for this last batch? I had a streak of high fg beers for a bit & found that where I measured the temp was resulting in a lower reading than was common throughout the mash...I was inadvertently mashing at a higher temperature.

Imo, if you have starters & proper temps throughout, all should work out fine. I also shake the hell out of my buckets, I'd double check all else before going with aeration as the culprit.

brew703 said:

I have a fermentation chamber- beer temp is 64 degrees.

Oxygenation could be the culprit as i only shake the carboy. I'll get a stone and a pump and try that but figured shaking the crap out of the carboy would be sufficient since i do it for 2-3 minutes before adding my yeast.

Click to expand...

I would guess this is the problem. I know there are guys out there that have been brewing for 200 years and have big beards and wear leather aprons (and some ladies too with even longer beards) who claim that shaking is enough, but the science doesn't bear it out and neither does my experience. True I have only been brewing since 2010, but, every time I tried to shake a beer it never turned out the way I wanted it.

Get a cheap oxygen setup going based on the little red oxygen cans. It's a must. 30 seconds of that is all your wort needs.

badmajon said:

Here's info on his yeast:

YEAST STRAIN: 1450 | Denny's Favorite 50

Back to Yeast Strain List

This terrific all-round yeast can be used for almost any beer style, and is a mainstay of one of our local homebrewers, Mr. Denny Conn. It is unique in that it produces a big mouthfeel and accentuates the malt, caramel, or fruit character of a beer without being sweet or under-attenuated.

Origin:
Flocculation: Low
Attenuation: 74-76%
Temperature Range: 60-70F 15-21C
Alcohol Tolerance: ABV 10%

Click to expand...

So, started off 4 points too high on a big beer with a medium attenuator. I would guess that accounts for the bulk of the discrepancy. The rest could be just the yeast having a bad day.

The yeast still got you down 51 points for close to 7% ABV.

badmajon said:

I would guess this is the problem. I know there are guys out there that have been brewing for 200 years and have big beards and wear leather aprons (and some ladies too with even longer beards) who claim that shaking is enough, but the science doesn't bear it out and neither does my experience. True I have only been brewing since 2010, but, every time I tried to shake a beer it never turned out the way I wanted it.

Get a cheap oxygen setup going based on the little red oxygen cans. It's a must. 30 seconds of that is all your wort needs.

Click to expand...

If he wants to test aeration, could he give it a shake now? He would risk off flavors from oxidation, but the beer is going to be pretty cloying as is.

badmajon said:

I would guess this is the problem. I know there are guys out there that have been brewing for 200 years and have big beards and wear leather aprons (and some ladies too with even longer beards) who claim that shaking is enough, but the science doesn't bear it out and neither does my experience. True I have only been brewing since 2010, but, every time I tried to shake a beer it never turned out the way I wanted it.



Get a cheap oxygen setup going based on the little red oxygen cans. It's a must. 30 seconds of that is all your wort needs.

Click to expand...

Is that using pure oxygen? I was thinking about getting an aquarium pump and .5 micron stone. I know pure oxygen is better but I don't know where to get it.

antony said:

I saw that you mentioned that mash temp was within 1-2 degrees for the entire mash...if you don't mind, what was the mash temp for this last batch? I had a streak of high fg beers for a bit & found that where I measured the temp was resulting in a lower reading than was common throughout the mash...I was inadvertently mashing at a higher temperature.

Imo, if you have starters & proper temps throughout, all should work out fine. I also shake the hell out of my buckets, I'd double check all else before going with aeration as the culprit.

Click to expand...

Mash temp was 153. I normally give a good stir every 15 minutes and check temps. it never got below 151. If I lose more than 2 degrees then i kick the heat on to get back to within .5 degree of mash temp then turn off the heat.
I just checked my thermometer (thermapen) and it's calibrated.

brew703 said:

Is that using pure oxygen? I was thinking about getting an aquarium pump and .5 micron stone. I know pure oxygen is better but I don't know where to get it.

Click to expand...

Here is a study that says shaking is just as effective. If this is right, you should be OK with a good shake and something else is causing the FG issue.

http://www.brewangels.com/Beerformation/AerationMethods.pdf

I know the studies are out there, but every time I shake, I get crap fermentation that sticks way too high. I mean hey, if it works, then okay, but my experience just does not bear that out.

Brew- you can get the red oxygen cans at Home Depot.

Check this out

http://www.williamsbrewing.com/WILLIAMS-5-MICRON-OXYGEN-AERATION-SYSTEM-P3668.aspx

Problem solved! The kit is $50, which seems like a small price to pay for such an important part of fermentation. One of the biggest problems with home brewing is controlling variables with DIY equipment and methods. If you do a 30 second blast of o2, you never have to consider it again as a possible factor as to why your beer didn't turn out.

Oh and this is also interesting (and of course the Irish prices quoted are double US prices) http://www.nationalhomebrewclub.ie/wordpress/oxygenating-wort-with-pure-oxygen/

badmajon said:

I know the studies are out there, but every time I shake, I get crap fermentation that sticks way too high. I mean hey, if it works, then okay, but my experience just does not bear that out.

Brew- you can get the red oxygen cans at Home Depot.

Check this out

http://www.williamsbrewing.com/WILLIAMS-5-MICRON-OXYGEN-AERATION-SYSTEM-P3668.aspx

Problem solved! The kit is $50, which seems like a small price to pay for such an important part of fermentation. One of the biggest problems with home brewing is controlling variables with DIY equipment and methods. If you do a 30 second blast of o2, you never have to consider it again as a possible factor as to why your beer didn't turn out.

Oh and this is also interesting (and of course the Irish prices quoted are double US prices) http://www.nationalhomebrewclub.ie/wordpress/oxygenating-wort-with-pure-oxygen/

Click to expand...

Thanks. I'll check out home depot today. So a 30 sec shot of pure oxygen is sufficient to aerate wort for yeast?

brew703 said:

Mash temp was 153. I normally give a good stir every 15 minutes and check temps. it never got below 151. If I lose more than 2 degrees then i kick the heat on to get back to within .5 degree of mash temp then turn off the heat.
I just checked my thermometer (thermapen) and it's calibrated.

Click to expand...

That just jumps out as a potential problem to me. When you turn on the heat it is likely that at least a portion of the mash got too hot and denatured the beta amylase. Once denatured, it doesn't come back and that would leave you with wort with lots of unfermentables, just as if you had mashed real high. For the next batch, insulate the mash tun with a coat or sleeping bag and leave it alone. No heat added.

RM-MN said:

That just jumps out as a potential problem to me. When you turn on the heat it is likely that at least a portion of the mash got too hot and denatured the beta amylase. Once denatured, it doesn't come back and that would leave you with wort with lots of unfermentables, just as if you had mashed real high. For the next batch, insulate the mash tun with a coat or sleeping bag and leave it alone. No heat added.

Click to expand...

I do insulate my kettle with an insulated coat and sleeping bag but the temps still tend to drop more than a few degrees- BTW i brew BIAB.
What is an acceptable reduction in temps? I figured more than a 2-3 degrees in an hour would be good. Any more than that then I would kick on the heat. When I do that I constantly stir the wort until the temps get to the mash temps. Cant see how part of the wort would get more heat since I constantly stir. But I guess it could.

brew703 said:

I do insulate my kettle with an insulated coat and sleeping bag but the temps still tend to drop more than a few degrees- BTW i brew BIAB.
What is an acceptable reduction in temps? I figured more than a 2-3 degrees in an hour would be good. Any more than that then I would kick on the heat. When I do that I constantly stir the wort until the temps get to the mash temps. Cant see how part of the wort would get more heat since I constantly stir. But I guess it could.

Click to expand...

I'm sorry but it wasn't obvious that you were BIAB and insulating the kettle. If your grains are milled fine, conversion is probably over before you turned on the heat the first time so that rules out the idea of denaturing. That leaves 2 things that I think could be problematic. One is the calibration of the thermometer that you use to determine the mash temp and that you are mashing much higher than you think. Thermometers can lose calibration. The second thing (it's a long shot but possible) is that you are keeping the beer in your fermenting chamber and that 64 degrees is causing your yeast to stop before the job is done. I usually start my beers at 62 degrees ambient which gets me to about 64 during the peak of fermentation, then when the activity slows down I let the beer warm to room temp. That higher temp is late enough in the ferment to avoid off flavors and fusel alcohol but encourages the yeast to complete the ferment.

brew703 said:

Thanks. I'll check out home depot today. So a 30 sec shot of pure oxygen is sufficient to aerate wort for yeast?

Click to expand...

It depends on flow rate, but id say 30-60 seconds is the standard people use around here. another thing i like about pure o2 is that usually it doesn't foam up as bad b/c its only a short time- try using an aquarium pump for 30 minutes and half your wort spills out as foam, and you are only supposed to use so much fermcap!

RM-MN said:

I'm sorry but it wasn't obvious that you were BIAB and insulating the kettle. If your grains are milled fine, conversion is probably over before you turned on the heat the first time so that rules out the idea of denaturing. That leaves 2 things that I think could be problematic. One is the calibration of the thermometer that you use to determine the mash temp and that you are mashing much higher than you think. Thermometers can lose calibration. The second thing (it's a long shot but possible) is that you are keeping the beer in your fermenting chamber and that 64 degrees is causing your yeast to stop before the job is done. I usually start my beers at 62 degrees ambient which gets me to about 64 during the peak of fermentation, then when the activity slows down I let the beer warm to room temp. That higher temp is late enough in the ferment to avoid off flavors and fusel alcohol but encourages the yeast to complete the ferment.

Click to expand...

Your second comment makes a good point and could be the issue. I have a batch in my ferm chamber now that has been about 63 degrees (recipe calls for 14-21 days @ 62). It's been in for 10 days. I think I over-pitched the yeast this time as I used US-05 (rehydrated) but some of the yeast stuck to the bottom of the jar so I added a bit more on top of my wort to compensate. At the 10 day point, there is still some activity. I'll let it go 14 days and check. If no activity I may take out of my ferm chamber and allow the temp to rise for another week to 10 days and see if that helps.

brew703 said:

Your second comment makes a good point and could be the issue. I have a batch in my ferm chamber now that has been about 63 degrees (recipe calls for 14-21 days @ 62). It's been in for 10 days. I think I over-pitched the yeast this time as I used US-05 (rehydrated) but some of the yeast stuck to the bottom of the jar so I added a bit more on top of my wort to compensate. At the 10 day point, there is still some activity. I'll let it go 14 days and check. If no activity I may take out of my ferm chamber and allow the temp to rise for another week to 10 days and see if that helps.

Click to expand...

Unless this is a high OG beer I'd suggest you take it out now while you have a lot of yeast in suspension with the idea that there would be more of them still active and willing to work. I usually let mine come to room temp at the end of a week and even that may be longer than optimal. Any off flavors would occur during the fast part of the ferment and you are well past that.

Will pull it out this evening and see if that helps.

I checked my two thermometers using the crushed ice/water method. They both register 32.2 and 32.5 respectively. I can only assume each one is fairly accurate.
With that said if a recipe calls for a mash temp of 153 at what temp will to high be bad for fermentation? Just trying to get a range.
I also do a 10 min mash out at 168. Could that be an issue?

Aristotelian said:

Here is a study that says shaking is just as effective. If this is right, you should be OK with a good shake and something else is causing the FG issue.

http://www.brewangels.com/Beerformation/AerationMethods.pdf

Click to expand...

This experiment was not comparing oxygenation with oxygen to oxygenation with air, it was only comparing different methods of oxygenation using different methods to introduce air into the water and measuring the percent oxygen saturation compared to water saturated air. The ppm oxygen with air will be less than the ppm oxygen using pure oxygen. Chris White's Yeast book compared ppm oxygen in wort to yeast performance and showed better performance with higher concentration of oxygen.

brew703 said:

I checked my two thermometers using the crushed ice/water method. They both register 32.2 and 32.5 respectively. I can only assume each one is fairly accurate.
With that said if a recipe calls for a mash temp of 153 at what temp will to high be bad for fermentation? Just trying to get a range.
I also do a 10 min mash out at 168. Could that be an issue?

Click to expand...

That could be an issue if your conversion isn't complete. The conversion will depend on the amount of time at mash temp and on the quality of the milling. If the grain isn't milled fine enough conversion may not be complete when you start heating to mash out. You can scoop out a bit of the grains and test with iodine to see if the conversion is over.

Thermometers that are accurate at ice/water temp may not be accurate at mash temps. I have a couple digital thermometers that match all the way to boil but I wanted one with a swivel head. That swivel head one would match the rest at room temp but was 7 degrees low at mash temp.

RM-MN said:

That could be an issue if your conversion isn't complete. The conversion will depend on the amount of time at mash temp and on the quality of the milling. If the grain isn't milled fine enough conversion may not be complete when you start heating to mash out. You can scoop out a bit of the grains and test with iodine to see if the conversion is over.

Thermometers that are accurate at ice/water temp may not be accurate at mash temps. I have a couple digital thermometers that match all the way to boil but I wanted one with a swivel head. That swivel head one would match the rest at room temp but was 7 degrees low at mash temp.

Click to expand...

After I did the ice water test I did a boil test and both registered 212. I guess I need to try the iodine test just to see.
The grains I have been getting have been milled really fine so I don't think its a conversion issue. Most of my brews I mash for 60 min then the 10 min mash out. I'll probably get a grain mill later this year to mill my own grains.