Why do I keep getting high OG readings?

[Thatpersson]

I have recently started brewing and have run into the same problem with all 3 of my batches. I seem to be getting a much higher OG than the recipe calls for.

My most recent batch is an oatmeal stout. The recipe says it should yield an OG of 1.057-1.059 and I got a reading of 1.072.

The recipe called for 8lbs Amber malt extract
8 oz chocolate malt
12 oz roasted barley
12 oz flaked oats
8 oz flaked weat
8 oz Crystal 120L
2 oz Hops

I boiled the grains in 2.5 gal of water and later and 2.5 gal water to the wort before beginning the fermentation process.

I have used my hydrometer in water to test it and got a reading of 1.00.

I was wondering if anyone has any idea as to why I am getting such a high OG? The first few batches tasted great. They were a bit sweet, but I drank them up nicely. I also noticed that my FG were a bit high. My last FG was 1.022, with a OG of 1.092! I have no clue why I am getting such high OG.

 

[BigB]

Are you measuring the OG after topping off and mixing really well? If not, that is the culprit. It is nearly impossible to screw up the OG by much on an extract batch unless you miss the top off water by a long shot. Also, please tell me you didn't boil the grains! The extract fine, but never the grains!

 

[Thatpersson]

Right you are! I did not boil the grains. Bad terminology on my part. I steeped them at around 150-160 for 30 minutes, then kicked up the heat, removed the grains, and upon boil I added the extract.

As far as topping it off goes... do you mean compensating for the water that is boiled off? I guess I dont. I start with 2.5 gal water in my brew pot for the wort. Then after cooling the wort I add another 2.5 gal of water before pitching the yeast. This may be my problem.

Do I add 2.5 gal water to the 2.5 gal of wort, then add more water to "top it off"? Then I mix this mixture up? (what method would you suggest to do this?) Also do I take the reading before pitching the yeast? I imagine I do...and I forgot to this last time.

Thanks for the quick response!

 

[BigB]

The grain will absorb about .1 gallon per pound of grain and you will also lose some due to evaporation. When I say top off, I say that you top off with water whatever volume of wort you have left (in the case of your stout you probably only had 2 gallons left after the boil) to 5 gallons. Cool the wort down to pitching temp. Then mix really well and take a hydrometer reading. Then pitch the yeast.

In your case of your stout, if you started with 2.5 gallons, then steeped the grains, then boiled, and only added 2.5 gallons of top off water, then your OG would be high because you didn't add enough top off water.

To mix, you can use a sanitized mash paddle, shake the fermentor, or some guys use a sanitized paint mixer with a drill.

 

[Hermit]

Right you are! I did not boil the brains.

That is a relief.....

 

[Thatpersson]

Thanks a lot BigB! You have been a great help. This step seems so obvious but I hadn't even thought about it! or read about it in any readings I have read or in the recipes I have picked up.

Do you think 3 pounds of grain, and thus .3 gal of water + the evaporated water could account for a difference between my OG and the recipes OG (which was about .01)?

I will be sure to do this for my next batch later this week once we transfer to the secondary.

Also I have another question for you... I have read that I should aerate my mixture quite a bit when mixing the wort and the water before pitching the yeast..would this be accomplished by vigorous stirring? I believe this step is to help provide oxygen for the yeast.

Anyways, thanks again BigB.

 

[BigB]

The shortage of water would definitely account for a high OG. The reason being is because you have the same amount of sugars in a smaller volume of water, thus being more dense. More dense=higher gravity. I quickly plugged your recipe into Beersmith and calculate that if you only had 4.25 gallons total, your OG would be 1.072.

As for aerating the wort, yes, vigorous stirring will aerate the wort. That is how I and many others do it. I usually stir it vigorously for about 2 minutes being sure to mix hard enough to draw air into the mixture.

 

[ajf]

What was the batch size for the recipe that you used?
If you are talking about a 5 US gallon batch, your original recipe should give an OG of about 1.074 if you used 8 lbs LME, or about 1.089 if you used 8 lbs DME
To get a gravity of ~1.058 you would have to make a 6.5g batch using LME, or a 7.5g batch using DME

As BigB said in post 4, the OG would only be correct if you added water to get to the recipe batch size.

One other thing to consider, is does the recipe state the batch size in US gallons? If it uses imperial gallons, you need to multiply the batch size by 1.2 to convert to US gallons.

[Edit] The above results were obtained by plugging the recipe into Promash. I get rather different results with Beersmith. I cannot determine right now which is right and which is wrong. I doubt I will have time to do the analysis before the weekend. [/Edit]

-a.

 

[BigB]

Good Point ajf. I assumed he meant LME, which Beersmith calculates his recipe at 1.059. But, replacing that with DME would drive up the OG to 1.070.... for a 5 US gallon batch.

 

[Thatpersson]

I am assuming that it is U.S. measurements as I am in America and the recipes are local. Thanks for the info guys. I will have to check out these calculators.

As far as aerating goes...the man that runs the brew store suggested pouring the water into the wort and then dumping that mixture back and forth between my brew pot and my fermentation bucket. I think this has worked well considering we have done it for our first 2 batches and the beers tasted fine.

edit:
Just checked the recipe...it didn't specify the type of gallon so I am assuming it is U.S.

 

[starrfish]

usually topping off results in LOWER OG since the water sits on top and hydrometer doesn't read the full mix... are you compensating for temp? hydrometers usually are calibrated at around 60 degrees. BUT the higher the temp the more you have to adjust up... Well I'm not sure now. At least your coming out high and you'll get more alcohol rather than reading low. win I guess, unless your trying to hit style markers like I do.

Replacing liquid extract with Dry could jump it up... I like dry any way found it produces a cleaner final product for me... if you do switch from liquid to dry back the total back a bit I used to know the % but haven't used liquid in so long I've forgotten the exact percent.

 

[BigB]

usually topping off results in LOWER OG since the water sits on top and hydrometer doesn't read the full mix...

True, but his main issue was that he was not compensating for grain absorbstion and evaporation. The mixing of the wort was discussed to provide him with the proper information to get accurate readings in the future.

the man that runs the brew store suggested pouring the water into the wort and then dumping that mixture back and forth between my brew pot

That is another good way to do it, so if it works for you, keep doing it that way.

 

[Thatpersson]

Great. I will let you know how the next batch goes. Should be sometime this week. You guys have been a lot of help. Especially you BigB, thanks.