Not Hitting My Final Gravity

[jkmeldrum]

Hi fellow AG'ers

I'm up to AG batch 6 I think, and one thing that I am finding as I get used to all my equipment is that I'm hitting my target OG quite well, and getting around 70% efficiency but I'm not getting my final gravity down low enough.

I've done a couple of wheat beers (with Wyeast 1056 Bavarian wheat), one Newcastle brown ale clone (with another Wyeast pack, London Ale I think), I've also since done an American Pale Ale with US-05 packet, and my latest brew which is in the fermenter - with a Nottingham Ale yeast packet.

None have hit the estimated FG as suggested by BeerSmith. The beer tastes pretty good, so I'm happy with that, but just for curiosity I would like to know if I'm only making mid-strength beer.

This is my latest brew:

6.00 kg Thomas Fawcett MO
0.50 kg Bairds Med Crystal

90min Mash started at 67C, only dropped about 1C over 90min mash. Batch sparged at about 75C with 14L of water.

90min boil
25g POR @ 60min
20g Amarillo @20min
20g Cascade @ 15min
1/2 Irish moss tablet @ 10min
20g Amarillo @ 5min
35g Cascade whole hops into primary after 4 days

After boil and contraction I ended up with about 23-24L in the boil kettle but there was a lot of suspended stuff that I couldn't strain through my valve so I only ended up with 19L into the fermenter.

Pitched dry yeast straight into fermenter at 23C Sat 23 April, started slowly bubbling through the airlock pretty quick and after 24 hrs was going pretty well and holding between 22-24C since over 7 days.

I've checked SG over the past few days as it has slowed, although still fermenting. Beersmith says I should get down to a FG estimate of 1.014. After a week I'm only down to 1.029 and slowing right down. I'll keep it in the fermenter for probably another week but I'm just wondering if there's anything I can do to improve this situation. Am I doing something wrong or missing something out?

I don't use an aeration stone or anything like that, so wondering whether it could be a lack of oxygen? I'm also using a refractometer that I bought online....I did check it against the hydrometer that I had prior to smashing it, and they were the same, and water reads zero, so I assume it's reasonably accurate.

Any advise would be appreciated.

Cheers

 

[manticle]

Suggested solutions:

Mash lower
Oxygenate well
step mash the sacch rest - eg 62 for 10-20 minutes, bump to 67 for the remainder
Calibrate hydrometer.
Check pitching rates
Do a fast ferment test on brews to work out expected attenuation

Also curious why you're fermenting at 24 degrees?

 

[bradsbrew]

+1 to All that manticle has said plus are you recalculating the reading from the refractometer?

 

[manticle]

Probably hit the nail there Brad. I don't use a refrac but a large number of people fall into the trap of not converting the value.

The presence of alcohol skews the reading Molly and needs to be calibrated using conversion charts.

 

[amiddler]

What was the OG prior to pitching the yeast there Molly?
Can't go wrong with manticle's advice, they seem the logical place to start.

Drew

 

[jkmeldrum]

Suggested solutions:

Mash lower
Oxygenate well
step mash the sacch rest - eg 62 for 10-20 minutes, bump to 67 for the remainder
Calibrate hydrometer.
Check pitching rates
Do a fast ferment test on brews to work out expected attenuation

Also curious why you're fermenting at 24 degrees?

Ok, so if I mash lower I end up with a drier beer, but that's because there are less unfermented sugars left behind as I understand it....meaning you have more converted to alcohol (and as a result a lower FG) is that right?

If I just 'strain' the wort through a fine sieve into the fermenter would that oxygenate enough do you think?

I currently mash in a 10Gal rubbermaid cooler, so to step mash can I add some of my strike water at the lower step temp and then heat up a bit with another addition of water? Not sure how this affects the grain/water ratio?

I'll look into calibrating my hydrometer and pitching rates.

As for the 24C fermentation, I don't have a fermentation fridge, so I just sit it on my kitchen bench, and that's what the little sticker says the temperate is....does that not sound right?

Cheers

Molly

 

[jkmeldrum]

+1 to All that manticle has said plus are you recalculating the reading from the refractometer?

No I'm not....well I don't think I am.....I thought you could just read off a refractometer as the few drops don't make much difference to heat compensation?

 

[jkmeldrum]

What was the OG prior to pitching the yeast there Molly?
Can't go wrong with manticle's advice, they seem the logical place to start.

Drew

Well I just read the OG value as being 1.060 from the refractometer....I didn't think I needed to do any conversion like you do for heat with a hydrometer....obviously I am wrong and need to look into this....thanks for all your replies (and so quick)!!!!

 

[bradsbrew]

Well I just read the OG value as being 1.060 from the refractometer....I didn't think I needed to do any conversion like you do for heat with a hydrometer....obviously I am wrong and need to look into this....thanks for all your replies (and so quick)!!!!

Nothing to do with heat Molly, once alcohol is present the reading need calculating, so during and post ferment you need to recalculate. I dont use beersmith but I am pretty sure it has a refrac calculator on it.

Cheers

 

[manticle]

Ok, so if I mash lower I end up with a drier beer, but that's because there are less unfermented sugars left behind as I understand it....meaning you have more converted to alcohol (and as a result a lower FG) is that right?

Pretty much. The enzymes that work at the low end of the 60s chop up starches into shorter chains. The enzymes at the higher end chop up into longer chains and produce more dextrins which are unfermentable and add to body and mouthfeel. The suggested stepped sacch rest gives the best of both worlds.

More scientific explanations can be found but the effect is basically as you suggest.

If I just 'strain' the wort through a fine sieve into the fermenter would that oxygenate enough do you think?

Probably not. Pouring from height will help. I no-chill and just shake my cube which according to texts won't give enough but I have no trouble with attenuation.

I currently mash in a 10Gal rubbermaid cooler, so to step mash can I add some of my strike water at the lower step temp and then heat up a bit with another addition of water? Not sure how this affects the grain/water ratio?

Yes you can. There is a strike water temperature calculator here http://www.grainandgrape.com.au/articles_o..._StrikeTemp.htm (scroll down) that you can tweak to include step mashing with water. Otherwise buy a decent immersion heater. I use mine for step mashing all the time although some people have had issues burning mash. No idea what the differences are but mine works beautifully.

You can also decoct.

I'll look into calibrating my hydrometer and pitching rates.

Don't forget the refrac conversion chart as suggested by Bradsbrew. probably the simplest and easiest explanation for your 'issue'.

As for the 24C fermentation, I don't have a fermentation fridge, so I just sit it on my kitchen bench, and that's what the little sticker says the temperate is....does that not sound right?

Cheers

Molly

24 is too high for most beers. 20 or lower is better (22 in a pinch can be done). Without a ferment fridge you can still keep things cool with sinks of water, iced bricks, wet towels, fans etc.

 

[jkmeldrum]

Pretty much. The enzymes that work at the low end of the 60s chop up starches into shorter chains. The enzymes at the higher end chop up into longer chains and produce more dextrins which are unfermentable and add to body and mouthfeel. The suggested stepped sacch rest gives the best of both worlds.

More scientific explanations can be found but the effect is basically as you suggest.



Probably not. Pouring from height will help. I no-chill and just shake my cube which according to texts won't give enough but I have no trouble with attenuation.



Yes you can. There is a strike water temperature calculator here http://www.grainandgrape.com.au/articles_o..._StrikeTemp.htm (scroll down) that you can tweak to include step mashing with water. Otherwise buy a decent immersion heater. I use mine for step mashing all the time although some people have had issues burning mash. No idea what the differences are but mine works beautifully.

You can also decoct.



Don't forget the refrac conversion chart as suggested by Bradsbrew. probably the simplest and easiest explanation for your 'issue'.




24 is too high for most beers. 20 or lower is better (22 in a pinch can be done). Without a ferment fridge you can still keep things cool with sinks of water, iced bricks, wet towels, fans etc.

Ok thanks...that gives me plenty to research....cheers

 

[jkmeldrum]

Nothing to do with heat Molly, once alcohol is present the reading need calculating, so during and post ferment you need to recalculate. I dont use beersmith but I am pretty sure it has a refrac calculator on it.

Cheers

Okay, wasn't aware of that, thanks.

Just when you think you know a thing or two about brewing, someone comes along and makes you realise you've still got a long way to go!!

 

[bradsbrew]

Just done a quick calculation on Brewmate.

Original gravity brix 14.7 = 1.060

current gravity 1.029 = 7.4 brix

Corrected specific gravity = 1.010

Looks pretty good to me.

Cheers Brad

 

[jkmeldrum]

Just done a quick calculation on Brewmate.

Original gravity brix 14.7 = 1.060

current gravity 1.029 = 7.4 brix

Corrected specific gravity = 1.010

Looks pretty good to me.

Cheers Brad

Wow.....I had no idea!

Just plugged the numbers back into the Beersmith Refractometer calculator. Didn't know about that one.

And you're right......Oh my god, what a diffeence, now I've got a beer with 5.35% Actual ABV, and still going.....thats right on target.

I love this forum.....and you guys of course.

Cheers

Molly

 

[Crusty]

Molly,
Since doing yeast starters with all my beers, I achieve a better attenuation & manage to drop a couple of extra points.
Had quite a few beers stop @ 1.013 & when doing starters, managed to get them down to 1.012 or 1.010.
As manticle said, mash in a bit lower, really agitate the wort before pitching your yeast & get that fermentation fridge.

 

[jkmeldrum]

Molly,
Since doing yeast starters with all my beers, I achieve a better attenuation & manage to drop a couple of extra points.
Had quite a few beers stop @ 1.013 & when doing starters, managed to get them down to 1.012 or 1.010.
As manticle said, mash in a bit lower, really agitate the wort before pitching your yeast & get that fermentation fridge.

Okay...I'll get on to that fridge in due course.....but next is another 50L pot and a brewstand, then kegging equipment, then I'll get the fermentation fridge. Who was it that said home brewing was cheap? Not me!

 

[MaltyHops]

Also ... I posted some charts some while ago that might be useful
- see Refractometer Sg-alcohol Correction Chart

Note that the first chart is for use where the OG is from 1030 to 1070,
second chart for higher OGs.

T.

 

[jkmeldrum]

Also ... I posted some charts some while ago that might be useful
- see Refractometer Sg-alcohol Correction Chart

Note that the first chart is for use where the OG is from 1030 to 1070,
second chart for higher OGs.

T.

That's excellent thankyou