Common cause of low SG?

I just did my second AG batch ever and as with the first my initial gravity (after diluting and cooling) was low, in the case of the second one VERY low. Recipe said 1.097 and I had 1.078.

The previous batch tastes fine just a lower ABV than i'd like, the second one has stabilized at the exact FG the recipe called for and also tastes fine in the secondary at 4 weeks, but the fermentation was far from vigorous.

I'm considering going back to extracts or mini-mashes since i'm clearly doing something wrong. Any ideas what, or is there something commonly missed that would cause low gravity? I was thinking i should have squeezed the bag although recipe clearly said not too, or sparged with hotter water or...who knows...

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there are many variables to to efficiency in all grain brewing. The most common culprit of poor efficiency that I have noticed is a less than ideal grain crush. I prefer the grain to be crushed and not just cracked.

You could also try a mash out by raising the temperature of the mash (after conversion has taken place) to 168 or so, then sparging with 170-175 water.

maintaining the proper mash temperature will also help in improving efficiency.

(after diluting and cooling)

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Rather than diluting to a volume, you should dilute to your expected OG (only if necessary of course). You can calculate -- or let your brewing software calculate -- the pre-boil gravity you need to reach your expected post-boil OG. If you get consistently lower efficiency with bigger malt bills, which is common, then try to plan on this when formulating your recipe. Or better, over build your recipe with the intention of diluting your pre-boil wort down a little to get the correct pre-boil gravity.

First questions should be what was the recipe efficiency and what was your actual brewhouse efficiency?

1.097 is a big beer. Efficiency with a large grain bill will be lower than a normal gravity (1.050 to 1.060) batch with the same technique.

Keep some DME on hand or settle for a smaller batch size until you dial in your process.

Edbert said:

I just did my second AG batch ever and as with the first my initial gravity (after diluting and cooling) was low, in the case of the second one VERY low. Recipe said 1.097 and I had 1.078.

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I haven't ventured into all grain yet so they may very well be right about efficiency.

However the diluting and cooling comment has me wondering. Did you dilute post boil to get to volume? Assuming your efficiency is correct if you topped off post boil and didn't mix well your SG will come out low.

Just a thought.

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Water. Water is the cause for your OG being too low. Every time. If you boil down to the gravity you are looking for (since gravity is a ratio of sugar to water), you'll never miss your gravity. Yes, you may only end up with 4 gallons of the beer, but it will be true to the recipe you intended. I had this happen this past weekend and I decided to carboy half of my batch (it was a 10 gal batch) and then boil the rest down to the gravity I was aiming for.

jCOSbrew said:

First questions should be what was the recipe efficiency and what was your actual brewhouse efficiency?

1.097 is a big beer. Efficiency with a large grain bill will be lower than a normal gravity (1.050 to 1.060) batch with the same technique.

Keep some DME on hand or settle for a smaller batch size until you dial in your process.

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I'm am embarrassed to say, I have no idea about the efficiency on the recipe or my kitchen stove "brewhouse". I think in this case I may have bitten off more than I can chew or was prepared for.

In all honesty I picked this one out of the giant recipe book at AHBS based upon is being a "Belgian ale" with very high ABV. Needless to say I was shocked by both the volume of grain and the price.

I've got a giant bag of DME in the freezer for making starters, is it as simple as adding that without affecting flavor or would corn starch have the same effect? I have a large cache of it for the Apflewein I keep making.

Reply to the "too much water responses...

Is it possible to take a hydrometer reading at ~200+ degrees? I thought either the temperature would burst the device or at least make the reading irrelevant.

I'm starting to think I am too noob and ill-equipped to make the move from extracts or MM to AG.

Find a gravity/temperature adjustment table. I got the one I use from one of my brewing books, you should be able to find one with a Google search. It will tell you how many points to add to your hydrometer reading for higher temperatures.

I use a refractometer ($25) to test before fermentation gravity. I use a small pipette to grab a bit of the boiling wort and b the time I drop it on the device, it's cooled. I imagine if you used a graduated cylinder and hydrometer, you'd have more trouble

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bboyeruga said:

I use a refractometer ($25) to test before fermentation gravity. I use a small pipette to grab a bit of the boiling wort and b the time I drop it on the device, it's cooled. I imagine if you used a graduated cylinder and hydrometer, you'd have more trouble

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I recently invested in a refractometer. Needless to say...its NICE! It's so awesome to be able to track your gravity while boiling. Wish I would have made that jump a long time ago.

Edbert said:

Reply to the "too much water responses...

Is it possible to take a hydrometer reading at ~200+ degrees? I thought either the temperature would burst the device or at least make the reading irrelevant.

I'm starting to think I am too noob and ill-equipped to make the move from extracts or MM to AG.

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I put my sample in the freezer to cool it down to around 60-70 before taking a gravity reading. It takes longer, but it's far more accurate this way. Most hydrometers are calibrated at 60*F.

Captain Damage said:

Find a gravity/temperature adjustment table. I got the one I use from one of my brewing books, you should be able to find one with a Google search. It will tell you how many points to add to your hydrometer reading for higher temperatures.

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I've found that the gravity reading temperature correction charts/calculators get increasingly more inaccurate the higher the temperature is. I was getting frustrated with how much my mash efficiencies were jumping all over the place... Yet my total brewhouse efficiency stayed pretty constant. It turns out that once I started letting my samples cool and then take the reading instead of adjusting for the temperature, my mash efficiencies jumped right in line with total brewhouse efficiency.

bboyeruga said:

Water. Water is the cause for your OG being too low. Every time. If you boil down to the gravity you are looking for (since gravity is a ratio of sugar to water), you'll never miss your gravity. Yes, you may only end up with 4 gallons of the beer, but it will be true to the recipe you intended. I had this happen this past weekend and I decided to carboy half of my batch (it was a 10 gal batch) and then boil the rest down to the gravity I was aiming for.

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True, but that doesn't solve the efficiency problem. You are just choosing the lesser of two evils. It is an efficiency issue whether you get the right volume and a low SG, or if you get the right SG and have a lesser amount. I'd say crush, especially for BIAB is the biggest thing. You can crush them as fine as you want bordering on flour since there is no worry of a stuck sparge. Also, I started increasing efficiency by mashing with 1 less gallon and using that gallon to rinse my grains after the mash.

OP I guess you are not serious about moving to AG if you plan on going back to extracts after a couple low OG batches. The learning never ends with brewing. I suggest reading up on AG and what some common practices are. Also there is a good sticky in the AG forum that explains some common issues with efficiency. There are many variables that affect efficiency, a few are water chemistry, mash chemistry, and grain crush. This forum is great for learning all that stuff.

Well...first of all you're doing a 1.097 gravity beer on your second try at all-grain and you're wondering why it didn't work out. Most people would try a lower gravity beer so they could get the hang of things and figure out how the system worked. It's not that they're scared to do big beers, it's that they would prefer not to waste money. I would stick to something around 1.060 and just figure things out for a bit. I'm not slamming you or trying to make you feel bad, it's just that even experienced all-grain brewers often have problems doing high gravity beers.

If you use some software like BeerSmith you can input information to make your recipes more accurate. Ingredients are like gas, and brewing equipment are like cars. 10 gallons of gas means two different things to a small car and a large truck, and the same goes for 10 pounds of grain on two different brewing setups. Test batches and brewing software help you get your "miles per gallon" or what we call efficiency. If Austin Homebrew Supply has their recipes built for an efficiency of 80% and you operate at 60% you will simply come up short. Many homebrewers can not push their efficiency higher so they just buy extra grain. Your best bet is to get the recipe you want to brew and enter it into software before you buy it so you'll know how much more grain to buy.

Again I highly recommend BeerSmith if you don't use it. It will tailor the recipe to you, you can make adjustments, and best of all they have a free trial period. They also have a forum and videos to get you using it right.

Stick with it. It's not an easy process for everyone; that's why the forums are here.

jjw5015 said:

True, but that doesn't solve the efficiency problem. You are just choosing the lesser of two evils. It is an efficiency issue whether you get the right volume and a low SG, or if you get the right SG and have a lesser amount. I'd say crush, especially for BIAB is the biggest thing. You can crush them as fine as you want bordering on flour since there is no worry of a stuck sparge. Also, I started increasing efficiency by mashing with 1 less gallon and using that gallon to rinse my grains after the mash.

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See, I find it much easier to keep efficiency high brew after brew with little effort thanks to my process. But yes, you are right that until you get your process down and have good efficiency, that is should be your main focus.

After that, you can have a fantastic mash efficiency, but screw it up by adding too much water or the boil not being as vigorous as you need (like on a warm/humid day). I'd say it is hardest to predict your boil off in the conditions you brew (unless you brew inside) than it is to keep your efficiency up. I create my recipes weeks ahead of time, but I can't tell how a brew day will go until I see how cooperative the weather is that day.

1st off thanks everyone! This is a great place you have built here.

I'm not throwing in the towel just yet, if i had totally given up on AG i would not have asked where i was going wrong

I was wondering if my kitchen stove and 3 gallon pot and BIAB equipment were to blame. I do not think i am ready for outdoor boilers of 5 or 10 gallons.

The choice of this recipe was not well researched, i like HG beers but this was larger than any i have made to date, most are in the 50 to 70 range. Also wanted to say thanks for the tip, i just ordered a refractometer!

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The mills at home brew stores crush hundreds of pounds of grain a day, which causes them to wear out over time. A $100 grain mill is a worthy investment as you will get a consistent crush each time. It will take me years to crush the amount of grain a LHBS will do in a week.