Final Gravity - Things To Check

[chrisluki]

Hey guys

Sorry for the long post, but this is bugging me and I think I have a gap ion my knowledge that I want fill!

Been hitting my projected OG readings nicely since I adjusted my mill to be a bit finer, but I think there might be something going astray with my methods from the mash tun onwards that is causing my FG readings to be a bit high.

Current batch is a Rogers Clone, in secondary, been fermenting about 10 days in total by now and it is showing a hydro reading of 1.020 which is a few points above my 1.013 target.

I have been doing some reading around the joint and wonder if you guys could comment on your thoughts about some of the causes I have found.

• Efficiency in Brewsmith - mine was set at 72% from scratch I think. I have read that this might be throwing out my calculated readings in the software. I dont really understand this, but this a typical brew for me...Batch size usually 20l with a Boil size of 23...I put in is 14 litres at initial mash, throw in another 17...but when it comes to bottling I am probably left with more like 13 litres? If I change my efficiency, will this do two things...give me more beer at bottling and raise my FG?
• Mash temperature - I have struggled with this a bit and probably in the last few brews have been more over the target temp than under, sparge water also over target temp. Could this affect it?
• Yeast - I have pretty much used S04 and S05 lately. I usually add the dry yeast to 300ml of water at 40 degrees (like Palmer says) and let it hyrdrate for half an hour or so before addidng to my wort. I have only used one packet each time, but as I said above, I am only fermenting something like 15l, so 1 pack should be fine?
• Aerating my wort - I have heard things about adding oxygen or really shaking the fermenter to add air into the mix. To make sure I have a clearer beer, latelty I have been doing a two-step filter/strain. I run out of my kettle after immersion chilling it, through a sanitised strainer into a sanitised bucket. Then I do the same thing with a strainer into another sanitised bucket and then same again into my fermenter. I figure that this combined with shaking the fermenter should aerate the beer enough...or it could be hurting my brew?
• Ferment Temp - My first few brews were closer to 16 - 18 degrees, but it has been warm lately so my beer might have been getting closer to 18 - 22. Maybe I need to find a cooler spot for the summer months...could I be putting the yeast to sleep?
• Primary to Secondary - I rack off after about 4 - 5 days if gravity is steady. Last couple of readings have been a little high. Maybe i should swirl the liquid a few days in and re-mix the yeast to see if it is still hungry? Maybe I should leave it for longer on the yeast cake?

That's all the things I can think of that may be affecting my fermentation. As I said, I really want to UNDERSTAND more about how these things might affect my beer, so happy to receive all feedback from you guys.

Thanks in advance

Cheers

Luki

 

[oglennyboy]

The times I had the same problems early on I found were directly due to the mash temp being high. When it was 68*C I always ended up with FG around 1.018-1.020. Spec grains made it worse from a sweet mouthy point of view.
The other comment is the rehydration of dry yeast at 40*, that seems pretty high, maybe you're wiping out most of the population and only a limited number of viable ones are left? I've never bothered rehydrating as there's views which say it doesn't matter, and tbh I've not noticed any probs.
Others might have better comments on the rest, but gee it sure seems like a lot of work with all the transferring to aerate. For 'ordinary' strength OG 1.048-1.052 ish I just let the tap drain directly into the fermenter, giving it a swirl every now & then. Bigger ones up to 1.070 I have a colander that sits in the fermenter opening, lets the wort spread over and fall thru the little holes. Ferments kick off after a day when I've pitched a proper amount.
cheers

 

[sponge]

• Efficiency in Brewsmith - mine was set at 72% from scratch I think. I have read that this might be throwing out my calculated readings in the software. I dont really understand this, but this a typical brew for me...Batch size usually 20l with a Boil size of 23...I put in is 14 litres at initial mash, throw in another 17...but when it comes to bottling I am probably left with more like 13 litres? If I change my efficiency, will this do two things...give me more beer at bottling and raise my FG?

I'm a little confused at what you're doing here.. 14 + 17 - 5 (grain absorption) - 10% evap - losses to trub = 20L (very rough calc)

But you're saying from your 20L into the fermenter, you're only bottling 13L?

Efficiency isn't really an issue with high FG though..

• Mash temperature - I have struggled with this a bit and probably in the last few brews have been more over the target temp than under, sparge water also over target temp. Could this affect it?

A higher mash temp will give a less fermentable wort and in result, a higher FG. How are you measuring your mash temp? Mash temp is a major factor in FG. Do you have a large amount of crystal in your grist?

• Yeast - I have pretty much used S04 and S05 lately. I usually add the dry yeast to 300ml of water at 40 degrees (like Palmer says) and let it hyrdrate for half an hour or so before addidng to my wort. I have only used one packet each time, but as I said above, I am only fermenting something like 15l, so 1 pack should be fine?

1 pack is fine for that batch size. 40'C is awfully warm for yeast though.. 04 and 05 should both get below 1.020 for a full strength beer though.

• Aerating my wort - I have heard things about adding oxygen or really shaking the fermenter to add air into the mix. To make sure I have a clearer beer, latelty I have been doing a two-step filter/strain. I run out of my kettle after immersion chilling it, through a sanitised strainer into a sanitised bucket. Then I do the same thing with a strainer into another sanitised bucket and then same again into my fermenter. I figure that this combined with shaking the fermenter should aerate the beer enough...or it could be hurting my brew?

Skip the straining steps. It might help aerate slightly, but you're increasing risk of infection using 2 additional buckets to transfer into the fermenter. Do you add fining agents to the end of the boil when you brew? Brewbrite/Koppafloc/whirlfloc? You can get clearer beer post fermentation through things like cold conditioning, gelatine and filtering. Less of an issue pre-ferment IMO.

• Ferment Temp - My first few brews were closer to 16 - 18 degrees, but it has been warm lately so my beer might have been getting closer to 18 - 22. Maybe I need to find a cooler spot for the summer months...could I be putting the yeast to sleep?

18-21'C is normally a good temp range for most ale yeast strains. How are you controlling and measuring your temps at the moment?

• Primary to Secondary - I rack off after about 4 - 5 days if gravity is steady. Last couple of readings have been a little high. Maybe i should swirl the liquid a few days in and re-mix the yeast to see if it is still hungry? Maybe I should leave it for longer on the yeast cake?

Shouldn't need to swirl the beer or anything with US05, it's a pretty good fermenter (I haven't used 04 for over 5 years so can't comment). I'd be looking at mash temp, along with yeast health/aeration at this stage.

Have you tested your hydrometer in room temp water (assuming you're using a hydrometer)? Does it read 1.000?

 

[chrisluki]

• Efficiency in Brewsmith - mine was set at 72% from scratch I think. I have read that this might be throwing out my calculated readings in the software. I dont really understand this, but this a typical brew for me...Batch size usually 20l with a Boil size of 23...I put in is 14 litres at initial mash, throw in another 17...but when it comes to bottling I am probably left with more like 13 litres? If I change my efficiency, will this do two things...give me more beer at bottling and raise my FG?

I'm a little confused at what you're doing here.. 14 + 17 - 5 (grain absorption) - 10% evap - losses to trub = 20L (very rough calc)

But you're saying from your 20L into the fermenter, you're only bottling 13L?

Efficiency isn't really an issue with high FG though..

• Mash temperature - I have struggled with this a bit and probably in the last few brews have been more over the target temp than under, sparge water also over target temp. Could this affect it?

A higher mash temp will give a less fermentable wort and in result, a higher FG. How are you measuring your mash temp? Mash temp is a major factor in FG. Do you have a large amount of crystal in your grist?

• Yeast - I have pretty much used S04 and S05 lately. I usually add the dry yeast to 300ml of water at 40 degrees (like Palmer says) and let it hyrdrate for half an hour or so before addidng to my wort. I have only used one packet each time, but as I said above, I am only fermenting something like 15l, so 1 pack should be fine?

1 pack is fine for that batch size. 40'C is awfully warm for yeast though.. 04 and 05 should both get below 1.020 for a full strength beer though.

• Aerating my wort - I have heard things about adding oxygen or really shaking the fermenter to add air into the mix. To make sure I have a clearer beer, latelty I have been doing a two-step filter/strain. I run out of my kettle after immersion chilling it, through a sanitised strainer into a sanitised bucket. Then I do the same thing with a strainer into another sanitised bucket and then same again into my fermenter. I figure that this combined with shaking the fermenter should aerate the beer enough...or it could be hurting my brew?

Skip the straining steps. It might help aerate slightly, but you're increasing risk of infection using 2 additional buckets to transfer into the fermenter. Do you add fining agents to the end of the boil when you brew? Brewbrite/Koppafloc/whirlfloc? You can get clearer beer post fermentation through things like cold conditioning, gelatine and filtering. Less of an issue pre-ferment IMO.

• Ferment Temp - My first few brews were closer to 16 - 18 degrees, but it has been warm lately so my beer might have been getting closer to 18 - 22. Maybe I need to find a cooler spot for the summer months...could I be putting the yeast to sleep?

18-21'C is normally a good temp range for most ale yeast strains. How are you controlling and measuring your temps at the moment?

• Primary to Secondary - I rack off after about 4 - 5 days if gravity is steady. Last couple of readings have been a little high. Maybe i should swirl the liquid a few days in and re-mix the yeast to see if it is still hungry? Maybe I should leave it for longer on the yeast cake?

Shouldn't need to swirl the beer or anything with US05, it's a pretty good fermenter (I haven't used 04 for over 5 years so can't comment). I'd be looking at mash temp, along with yeast health/aeration at this stage.

Have you tested your hydrometer in room temp water (assuming you're using a hydrometer)? Does it read 1.000?

Thanks for all this Sponge!!

Some answers for you...

• YEs, after all that I am only bottling around 13l
• Mash temp, yeah i think it is my issue too. Initially it was too low cos i didn't pre-heat the keg, then I was paranoid of getting below 65 degrees so I was pouring it into a preheated keg at around 80 degrees and then throwing in grains...sometimes it would be as high as 72-75. Then if it was any lower than 68 i was throwing in the heating element. TIme to stop this me thinks!
• What temp do you suggest i hydrate my yeast at, or maybe just use the sprinkle on the wort method?
• I have been using whirlfloc and trying to do a whirlpool to limited success. I have filter in my kettle that gets a bit of the crap out, but was trying to double filter if you like. I have just secured a bar fridge to do a cold crash for the first time on my current beer.
• TEmp control in fermentation is non existent. I have a heat belt for winter and try and keep it cooler in the summer by putting it in a cool cupboard under the stairs. Temp check is by those stick on thermometers.
• Hydrometer is all good, tested it.

Gonna look at my mash temp as my numero uno priority i think!

Thanks again.

 

[sponge]

Mash temp is almost definitely your culprit then. 68-72 will produce a very dextrinous wort and won't ferment as far as you're expecting.

Don't worry at all if it goes below 68. I am sure I have read of brewers on here who primarily do a single step at 63-65, because they like their beers drier. 66 is normally a pretty good temp to hit for a mid-bodied brew.

Aim for 65-66 in your next brew (keep the recipe the same as one of your current 1.020 ones and get rid of the extra filtering steps) and let us know how the FG turns out.

As a side note, those stick on thermometers are notorious for being inaccurate. Even if you keep the fermenter in a large plastic container filled with water, add ice bottles to cool it down and measure the temp of the 'water bath'. Try and keep the water around 18'C, which will probably hold your beer at around 20'C. That was how I controlled my fermentation temps prior to getting a fermenting fridge/chamber (which is a must-have IMO) with decent success.

 

[manticle]

Rehydrate according to individual manufacturer's instructions, not palmer's 'one shoe fits all' guide which may have been revised since anyway. Is it the one that suggests adding a tsp of sugar?

Regardless you'll find fermentis recommend rehydrating their ale yeasts under 30 (27-ish from memory).

 

[Droopy Brew]

Definitely way too high on the mash. Your brew calculator should be able to tell you exactly what to heat the strike water to to get a desired mash temp.
All you do is put in the temp of the grains at ambient and the desired temp and the amount of water in the mash. I use Brewmate but I imagine brew smith should tell you exactly the temp to heat that strike water to.

Rehydrating at 40C is akin to yeasticide. Stop it, stop it right now.

250ml of 25C water or thereabouts and a teaspoon of malt extract for an hour or two while the wort cools to pitching temp (I usually have a few deg to drop even after chilling) and they will be hungry and healthy.

 

[stux]

Definitely look into your Mash temp. I like a 66C mash myself, but you need to have a good thermometer that you can then calibrate everything else from. As it turns out my early AGs were having FG problems. Eventually I traced it back to my mash thermometer being a couple of C out.

Eventually I got sick of rubbish thermometers and bought a Thermapen

Once you sort out your primary problem, getting an O2 setup will allow you to get the final 2 points of gravity down to the theoretical attenuation of the yeast.

 

[WitWonder]

Um, what's your OG? You've mentioned your FG which is useless without your OG to make a calculation. If you're bottling only 13 litres 1.020 could well be final gravity. How much grain are you using?

 

[chrisluki]

Um, what's your OG? You've mentioned your FG which is useless without your OG to make a calculation. If you're bottling only 13 litres 1.020 could well be final gravity. How much grain are you using?

OG is going fine. Recipe stated 1.041 and I got 1.042, or vice versa.

Recipe details are below...

Type: All Grain
Batch Size: 20.00 l
Boil Size: 24.16 l
Boil Time: 60 min
End of Boil Vol: 21.32 l
Final Bottling Vol: 19.00 l
Fermentation: Ale, Two Stage
Date: 21 Nov 2014
Brewer: Chris
Asst Brewer:
Equipment: My Equipment - 3 Vessel Stainless Kegs
Efficiency: 72.00 %
Est Mash Efficiency: 73.8 %
Taste Rating: 30.0



Est Original Gravity: 1.042 SG
Est Final Gravity: 1.013 SG
Estimated Alcohol by Vol: 3.8 %
Bitterness: 23.5 IBUs
Est Color: 41.5 EBC
Measured Original Gravity: 1.046 SG
Measured Final Gravity: 1.010 SG
Actual Alcohol by Vol: 4.7 %
Calories: 427.1 kcal/l



Mash Profile
Mash Name: Single Infusion, Full Body, No Mash Out
Sparge Water: 17.73 l
Sparge Temperature: 75.6 C
Adjust Temp for Equipment: FALSE
Total Grain Weight: 4.00 kg
Grain Temperature: 22.2 C
Tun Temperature: 22.2 C
Mash PH: 5.20



So I kind of lose 6 litres somewhere????? How do i stop that?

 

[WitWonder]

OK Well I'd suspect it's your mash temp, as others have said. Your volume into your fermenter consists of the initial volume, minus your grain in kg (1kg of grain will roughly absorb 1L of water), minus your boil off amount (if you don't know this, assume 10% per hour loss initially but you can work it out pretty easily after your first brew - it's the difference between your initial volume minus your grain kg and the volume into the fermenter). There's other losses to consider (trub left in the kettle, wort in the plate chiller) but boil off and grain absorption are the main ones. Adjust the brewsmith actuals to reflect these, not the other way around.

 

[schtev]

I don't understand how or where you are losing so much volume. Do you have measurements from the various stages of your brew? If not, you really should be measuring your:

• initial mash water volume
• sparge volume (I'm not sure if this is important, perhaps a 3V brewer can confirm this one)
• volume at the start of the boil
• volume after the boil (this will help you calculate how much you boil off in your system)
• volume into fermenter (if you are purposefully leaving behind some wort and trub from your boil then you will lose more volume here)
• volume into bottles (you will lose a few litres from fermenter trub)

From this you will be able to work out where you are losing the majority of your water and figure out what you need to fix.

 

[marksy]

How much water are you mashing with? You are adding 17L of sparge water, and with your Eff and SG I`d say your using 4.5kg of grain. So that 4.5kg x 2.5 water to grain ratio. So 11L, and add that to sparge and minus 5L to grain absorption. So your at like 23L into kettle at boil, and I`d say you`d lose more the 2L over an hour boil, more like 4-5 on a good boil.

Work out all your dead spaces. Then start with your target volume into FV and go backwards. You will find all the correct numbers you require.

 

[Truman42]

• I have just secured a bar fridge to do a cold crash for the first time on my current beer.
• TEmp control in fermentation is non existent. I have a heat belt for winter and try and keep it cooler in the summer by putting it in a cool cupboard under the stairs.

If you have a fridge for cold crashing, use it for fermentation control as well.

 

[chrisluki]

If you have a fridge for cold crashing, use it for fermentation control as well.

Not sure if my fridge is that smart?

 

[Mardoo]

Make it so.

http://www.ebay.com.au/itm/231457440447%20

 

[sponge]

Mind. Blown.

 

[Truman42]

Make it so.

http://www.ebay.com.au/itm/231457440447%20

Then once youve brought it follow these instructions to wire it up. But if your not confident with electrical wiring get a sparky or mate who is.

http://aussiehomebrewer.com/topic/66428-stc-1000-in-pictures/