Struggling to hit final gravity with using grainfather G40

[tomasz.ciesla]

hi, I'm brewing full grain using G40 and then fermenting using GF30 with Kveik. Each fermentation ends 0.002-0.003 points above expected value. The resulting beer is in my opinion touch too sweet and leaves sticky mouths after drinking one glass. Any idea why? Example brews:
Pale Ale + 5% Oats, 60 min@62°C + 10min mash out @75°C. Fermenting with Kveik Voss @35°C, fermentation was done after ~36h. 1.051 -> 1.012, expected <1.01
Pale Ale + 5% Caramunich + 5% Oats, 60 min@62°C + 10min mash out @75°C. Fermenting with Kveik M12@35°C, fermentation was done after ~36h. 1.053 -> 1.012, expected <1.01
Bohemian Pilsner + 5% Munich, 60 min@65°C + 10min mash out @75°C. Fermenting with Kveik Lutra@22°C, fermentation was done after ~60h. 1.053 -> 1.013, expected ~1.01
Strike in temperature = mashing temperature. I do mix grain 2-3 times during mash, it boosts brewing efficiency up to ~85%, I do press grain after sparging so I don't have to wait so long. I do quadruple recommended yeast nutrition dose for Kveik, brews 2&3 with Irish Moss. I do aerate the wort using stone and aquarium air pump. I pitch the yeast using method recommended by David Heath: after transferring 3l I sprinkle yeast on the wort and splash wort on it. So far I had no issues with starting the fermentation.
I measure pre fermentation and final gravity using refractometer (check with distilled water and sugar water) and calculator correcting for alcohol content
Pete Drinks ABV Calculator – Refractometer & Hydrometer

 

[IslandLizard]

Each fermentation ends 0.002-0.003 points above expected

You mean 2-3 points? e.g, FG is 1.012 vs. expected 1.010. <== observe, that 3rd decimal is crucial.

Are you plugging %Brix units or SG units (read from your refractometer) into that calculator?
Mind, the SG units on the refractometer's scale are not trustworthy, go by %Brix only.

Have you tried measuring OG and FG using a hydrometer, to compare?

When using a hydrometer there are no formulas, what you read is what it is:

• as long as your sample is at, or close to the calibration temp of the hydrometer
• you've checked/verified calibration with distilled water at calibration temp., which is usually printed on the paper scale.
• It's also recommended to degas the sample when measuring fermented samples.

We usually find 1-3 point deviations from expected to be very acceptable in homebrewing.
Maybe you're mashing at a little higher temperature or using grain that's not quite as fermentable, among a dozen other possible causes, resulting in slightly higher FGs than the recipes'.

As an alternative, or just for kicks, try this calculator at Brewer's Friend (use Part II) and compare results:
https://www.brewersfriend.com/refractometer-calculator/

 

[tomasz.ciesla]

yes, 1.01 = 1.010, I miss last 2-3 points
I measure always using Brix. I did check calculator using hydrometer once and I use refractometer for convenience.
Extra sugar which I want to get rid off (probably unfermentable one) shows mainly as sweeter beer and sticky lips feeling.
I did try different malts and I end up always in the same place. Next brew I'll take a closer look at the temperature at output of G40 pump.

 

[PCABrewing]

I'd be sure to verify mash temp.
Also, how are you calling fermentation done, what is your criteria?

 

[IslandLizard]

Extra sugar which I want to get rid off (probably unfermentable one) shows mainly as sweeter beer and sticky lips feeling.

And dextrins.

Although 20-30% higher, I seriously doubt we (people) can detect a difference of 2-3 points in FG (1.012 or 1.013 vs. 1.010) by mouthfeel and taste without comparing the samples side by side. A "triangle test" would be best, to pick out the different one among the 3 samples.

I'd be sure to verify mash temp.

Definitely that.^

These AIO systems have some unique aspects (and associated issues) not common in for example a converted cooler mash tun.
Recirculation during the mash means wort (in the bottom) is being heated to overcome heat loss higher up in the system. To reduce the amount of heat that needs to be added you could start by insulating the whole Grainfather including the recirculation components, as well as the lid.

 

[tomasz.ciesla]

Also, how are you calling fermentation done, what is your criteria?

I keep beer in fermenter for 7-9 days. I sample FG when there's no activity in the airlock: typically 36h@35°C using Kveik. then I double check during transfer at 7-9 days. I see no change between those two samples.

wort (in the bottom) is being heated to overcome heat loss higher up in the system

That may be the issue here. I'll brew next time with strike in temperature and I'll have a closer look at temperature and heater's power indicator. It might be the case that the wort is heated up locally, at the bottom of g40, to higher temperature activating locally alpha enzymes.

 

[IslandLizard]

It might be the case that the wort is heated up locally at the bottom of g40 to higher temperature activating locally alpha enzymes.

It is being heated during recirculation, on the bottom.

Alpha-amylase is the main, mostly random, long-chain starch chopper, with a much higher denaturing temp than Beta. She creates mostly large, unfermentable chunks (dextrins).

Beta-amylase categorically breaks down those dextrins and higher sugars (polysaccharides) into fermentable sugars.

Steady denaturing of Beta-amylase, due to higher local wort temps, around the heated bottom, will cause the wort to become less fermentable. IOW, heating the wort during recirculation causes the same Beta-amylase denaturing as if you had mashed a few degrees higher without recirc.

 

[tomasz.ciesla]

Thanks for help! I'll try to nail it and I'll post results after next brew. I'll contact Grainfather is it a known issue of G40. Maybe G40 needs insulating jacket as G30

 

[IslandLizard]

Thanks for help! I'll try to nail it and I'll post results after next brew. I'll contact Grainfather is it a known issue of G40. Maybe G40 needs insulating jacket as G30

Just wrap a thick blanket or (old) sleeping bag around the whole thing while mashing, even while boiling. Remove it when you start chilling.

Yes please, keep us posted, I doubt you're the only one battling this.

 

[Spivey24]

Check your mash temperatures with a thermometer. I have the G40 and find the temps all over the place even with the recirc pump running. Mashing at 62°C is at the low end so if the mash is off a little it will be a bit too low. I typically set the temp a couple degrees higher in the recipe than I want to compensate.

I always do a step mash too. Easy with the G40. Easily hit 1.008 to 1.010 on 99% of brews. 63 and 71 30-40 minutes each and skip the mash out. Beers are never thin.

Gives the beers a couple extra days in the fermenter. Airlock activity is not a good indicator of done. Sometimes those last couple points can take some time. Buy yourself a Tilt or similar to better track gravity.

You didn’t say how you package or how long you condition or lager, but I have noticed that a couple of the Pilsner’s that came out a bit too sweet improved with longer keg conditioning on full carbonation.

And finally I ditched the basket for 11 gallon/40L batches on the G40 and use a brew bag instead. I got sick of messing with the recirc pump and having it overflow through the damn handle holes in the basket. With the bag I can run the pump at full and have a thinner mash which helps keep the temp a little more stable.

 

[tomasz.ciesla]

You didn’t say how you package or how long you condition or lager, but I have noticed that a couple of the Pilsner’s that came out a bit too sweet improved with longer keg conditioning on full carbonation.

I keep beer in keg in fridge @12°C under CO2

I got sick of messing with the recirc pump and having it overflow through the damn handle holes in the basket.

Put more attention during dough-in, then after 5 mins of mashing you can mix grain again. There's no top plate in the system so it takes no time

 

[tomasz.ciesla]

Just wrap a thick blanket or (old) sleeping bag around the whole thing while mashing, even while boiling. Remove it when you start chilling.

Yes please, keep us posted, I doubt you're the only one battling this.

btw I don't measure and correct PH during mash, can it affect FG too?

 

[jambop]

hi, I'm brewing full grain using G40 and then fermenting using GF30 with Kveik. Each fermentation ends 0.002-0.003 points above expected value. The resulting beer is in my opinion touch too sweet and leaves sticky mouths after drinking one glass. Any idea why? Example brews:
Pale Ale + 5% Oats, 60 min@62°C + 10min mash out @75°C. Fermenting with Kveik Voss @35°C, fermentation was done after ~36h. 1.051 -> 1.012, expected <1.01
Pale Ale + 5% Caramunich + 5% Oats, 60 min@62°C + 10min mash out @75°C. Fermenting with Kveik M12@35°C, fermentation was done after ~36h. 1.053 -> 1.012, expected <1.01
Bohemian Pilsner + 5% Munich, 60 min@65°C + 10min mash out @75°C. Fermenting with Kveik Lutra@22°C, fermentation was done after ~60h. 1.053 -> 1.013, expected ~1.01
Strike in temperature = mashing temperature. I do mix grain 2-3 times during mash, it boosts brewing efficiency up to ~85%, I do press grain after sparging so I don't have to wait so long. I do quadruple recommended yeast nutrition dose for Kveik, brews 2&3 with Irish Moss. I do aerate the wort using stone and aquarium air pump. I pitch the yeast using method recommended by David Heath: after transferring 3l I sprinkle yeast on the wort and splash wort on it. So far I had no issues with starting the fermentation.
I measure pre fermentation and final gravity using refractometer (check with distilled water and sugar water) and calculator correcting for alcohol content
Pete Drinks ABV Calculator – Refractometer & Hydrometer

I do not use a G40 but I have a S40 and I think that the temperature gradient in the system is not accurate. I was getting final gravities that were higher than expected from my system. I got fed up with that and decided to try stepped mashing so instead of say single infusion mashing at 66C I changed to mashing in at 62C for 20 mins then upping to 65 C for 30 mins then up to 68C for 30 mins and finally 75C for 10 mins . I find that using this method I am hitting my expected final gravity within 0.001 now.

My thinking behind doing this was this. Below the grain basket in S40 there is about 6L of brew liquor which is sitting at strike temperature so for me usually somewhere about 72C for most brews. You dough in your grist at 72 C and hit your 66 C mash temp... fine... then turn on the recirculation pump and start adding this strike temperature brew liquor to the mash and immediately start to increase the temperature of your mash. Now I do not know if this is why I was not getting right final gravity but it could be ? So the question is does the G40 have a void volume of brew liquor below the grain basket similar to the S40 ? One other thought I have which I think helps is to make sure you grist is at a decent temperature, I try to be at 25C , this ensures that your strike temperature is lower than if say the grist was at 15C . This again keeps the mash temperature down a bit when you start to pump the wort over the mashing grain bed .
The above could be a lot of baloney but it is what I have started doing .
edit
Another poster talked about hydrometer reading and calibration. I found my hydrometer read 0 Plato with dH2O and 0.5 Plato with brew liquor which is 0.002 sgu but I was getting greater FG differences than that.