Attenuation Issues

[PK]

I have a long standing issue with beers attenuating properly and after my latest one (1.02 instead of 1.01) it's driving me mad at this stage.
Whether it's ale or lager yeast I'm regularly finishing 5-10 points above the manufacturer number for FG when you'll read about most other people hitting or even exceeding the spec.
- pH is always in a good range (5.2 to 5.5).
- I've tried under pitches, on spec pitches, and over pitches with the same results (note: I only use dry yeast).
- I've tried not ramping temp or ramping temp in varying ways (after it's flatlined, with 10 points to go, etc) with the same results.
- Mash temp has been checked with a calibrated thermometer (my Brewzilla is off bt 2.5 degrees but I know about this and compensate.
- Fermentation temp is controlled and has been verified also.
Anyone had this issue before and resolved it with any success? Cheers.

 

[Sadfield]

How much calcium is in your water?

 

[PK]

How much calcium is in your water?

From a water analysis I got done by WHC Labs I have 25ppm in my base water (it's a well, so not sure how accurate it would always be, but a test I had got done 2 years previously by ALS Global said it was 30ppm).

My last 5 brews have had 83, 45, 62, 84, and 75 respectively in their adjusted profiles.

 

[Sadfield]

I'd suggest doing a full boil brew with DME. If it attenuates fully, then you'll know the issue is likely with wort production, possibly something like low FAN levels.

 

[foxy]

Mash temperatures can vary even just inches apart randomly checking the temperature every now and again doesn't cut it. As you are using the Brewzilla G4 I would suggest checking the temperature constantly around the top for the first 15 to 20 minutes it is surprising how much temperature difference you can uncover.
Final gravity, do you degas the sample? Do you pressure ferment? a couple of ways to degas a sample is to pour the sample into a cup, slosh backwards and forwards at least 10 times then leave for several hours to settle.
Pro brewers pour the sample through a coffee filter before taking a reading.

 

[PK]

Mash temperatures can vary even just inches apart randomly checking the temperature every now and again doesn't cut it. As you are using the Brewzilla G4 I would suggest checking the temperature constantly around the top for the first 15 to 20 minutes it is surprising how much temperature difference you can uncover.
Final gravity, do you degas the sample? Do you pressure ferment? a couple of ways to degas a sample is to pour the sample into a cup, slosh backwards and forwards at least 10 times then leave for several hours to settle.
Pro brewers pour the sample through a coffee filter before taking a reading.

I'd be hoping they'd be fairly consistent as I'm using the RAPT add-on thermometer that's measuring the top portion of the mash. I'll take a look at the degassing though as it's something I don't do. I never ferment under pressure but there could probably still be some CO2 in solution from the fermentation. Thanks.

 

[Brew_DD2]

Maybe a stupid question, but how are you measuring your gravities?

 

[foxy]

I'd be hoping they'd be fairly consistent as I'm using the RAPT add-on thermometer that's measuring the top portion of the mash. I'll take a look at the degassing though as it's something I don't do. I never ferment under pressure but there could probably still be some CO2 in solution from the fermentation. Thanks.

If you aren't stirring the mash initially there will be inconsistencies within the mash. I don't mash with the lid on and have recently discovered that the temperature at the top gets higher than the bottom of the mash tun due to the insulation of the foam on the top of the mash. I closely monitor the temps with two probes and have the return pipe at full throttle.

 

[Agentgonzo]

I never ferment under pressure but there could probably still be some CO2 in solution from the fermentation

Dissolved CO2 in solution won't affect the SG of the wort/beer in any significant way (ie, the difference is way below what you can detect with your hydrometer). As long as there aren't bubbles rising up and hitting the hydrometer or clinging to the side of it, you're fine. If there are bubbles clinging to the hydrometer, give it a spin to dislodge them

 

[Sadfield]

I think you'd need to be more than 3-6°C out with mash temperature to see a 5-10 gravity point discrepancy, and only then if you're only using something like Windsor, that can't assimilate maltotriose.

Also, if you were measuring hotter at the top, than the rest of the mash, fermentability would increase on what was predicted.

 

[dmtaylor]

Which yeast strains have you been using exactly? This matters a lot.

I think the top of the mash might measure cooler than the middle of the mash, but I could be wrong. Measuring in multiple points using a stick thermometer and taking the average, and/or stirring frequently, will improve the accuracy of your mash temperature readings.

 

[JockyBrewer]

Three simple questions:

Are you consistently using the same yeast strain, or is this issue across strains?

Really dumb question... but have you put your hydrometer in plain water to check it's reading right? Last person that complained of the same issue found that he wasn't filling up his hydrometer jar enough, so actually when trying to read FG the hydrometer was sitting on the bottom of the jar

Finally, what's your mashing process? I know someone that has had the same issue, and eventually realised it was because he was doing quite a large scale BIAB and it was taking him quite a long time to get the grain fully hydrated (up to half an hour). That meant that quite a lot of the grist was sitting at a high temperature for quite a long time.

 

[stubrewworx]

I'm having similar results. Granted some beers were using windsor, but a windsor with notts/gervin only achieved 70% aa.

My latest, using whc old English was approx. 67% aa.

Best I've had is 71% aa with s04. Floccuated well too.

I do ferment in the kettle and the wort isn't aerated prior to pitching?

Next brew uses kveik, so we'll see how that does.

 

[Sandimas]

How are you storing your yeast and how old is it? I accidentally opened a packet of Wheat Beer yeast when brewing an ale, re-sealed it and kept it in the fridge, only managed a measly 49% attenuation when I got round to using it.

I find that some dark beers finish high too.

But using a standrd yeast such as S04, US05 or MJ Liberty Bell you should get 70-80% attenuation. Suggest trying a simple brew (pale ale malt with a bit of crystal) with one of these yeasts.

 

[hoppyscotty]

How are you measuring your gravity? bit of a long shot here as I'm sure you've got this covered, but I used to think I was not fully attenuating and was always constantly 5 or more points higher on FG reading...always used refractometer to measure OG and a cheap hydrometer for FG....did a test of the hydrometer in distilled water and it was reading 4 points high, so compensating all my previous FG readings for this error I was either spot on with FG or only 1-3 points off, which is close enough...I've since got a better hydrometer which is bob on and FG comes in spot on now, but if you've not already checked out yours then it might be a good idea to do so to if only to rule it out.

The biggest issue I have with attenuation is with really high gravity worts, once I'm above about 1.065 to 1.070 then I struggle to fully attenuate...don't do alot of high gravity beers so not something I'm bothered about but would be nice to crack that one one day.

 

[Sadfield]

Yeast health is everything, regardless of how well, or badly you make wort. IF there's sugar in the wort, why isn't it being utilised?

https://beerandbrewing.com/dictionary/bkLLf5XnkJ/


If we looked at it from a different angle and wanted to take a working recipe and make it finish 5-10 points higher, we'd have to employ a number of dramatic changes to achieve it.

 

[JockyBrewer]

The biggest issue I have with attenuation is with really high gravity worts, once I'm above about 1.065 to 1.070 then I struggle to fully attenuate...don't do alot of high gravity beers so not something I'm bothered about but would be nice to crack that one one day.

For me it was a gradual process, in order of importance:

Yeast selection (Edinburgh/Scottish ale yeasts always under attenuated slightly, not as much as Windsor though)
Yeast health
Mash temperature consistency
Mash pH

 

[Hazelwood Brewery]

@PK is your OG always spot on?

If your OG differs from the recipe you’re following you would expect the FG to also differ. This could explain smaller changes but 10 points difference in FG is a hefty discrepancy so there’s more going on there.

What’s your mash schedule, is it a single infusion or are you step mashing? For how long and at what temperature?

Do you brew the same recipe and is the discrepancy consistent for the same beer?

 

[stubrewworx]

I'm having similar results. Granted some beers were using windsor, but a windsor with notts/gervin only achieved 70% aa.

My latest, using whc old English was approx. 67% aa.

Best I've had is 71% aa with s04. Floccuated well too.

I do ferment in the kettle and the wort isn't aerated prior to pitching?

Next brew uses kveik, so we'll see how that does.

Just finished brewing today. Hydrometer I thought was calibrated was actually 4pts out. Compared to refractometer and another Hydrometer.

If it was 4pt out when I read the fg of my last brew, than I actually achieved 71% aa with whc old English. And my strong bitter is 4.7, not 4.5!!

 

[crescent city Mike]

Any control of the degree of attenuation should be made during mashing, and not by attempting to adjust matters subsequently.