Help, FG is high...

So...

I was making a run at Beer Muncher's OktoberFAST and after three weeks in the fermentor today, I added corn sugar and was ready to bottle.

Then I check the gravity, and it was 1.030. Supposed to be 1.017.

The fermentation in the first four days was wild and fun, then quiet for the next couple weeks.

I never suspected that I was stuck or something.

The beer tastes great, but I'm worried that if I bottle, they will all start blowing up.

Do I finish bottling or rack it back into the fermentor and give everything a big shake.

By the way I fermented at about 68 the whole time.

Too high, rack it back in to the fermenter and warm it up. S-04 can get lazy if the temps drop, I'd warm it to the mid 70's to let it finish up.

You added corn sugar and THEN you checked your gravity?

You don't know what the final gravity of your beer is then. You are measuring the beer with added corn sugar.

To KNOW what the gravity is, let it sit for another week or two so it can ferment out the additional sugar. THEN check the gravity BEFORE any additional sugars are added. Make sure the wort sample is around 70 F.

Wayne1 said:

You added corn sugar and THEN you checked your gravity?

You don't know what the final gravity of your beer is then. You are measuring the beer with added corn sugar.

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I whole-heartedly agree that those should have been reversed. The thought that fermentation wasn't done after three weeks just hadn't occurred to me and I was being lazy.

Are you suggesting that 5oz of corn sugar can push the gravity of five gallons by 13 points? That seems a little steep.

It depends on how well mixed your sample was. It could be that the sample you pulled had quite a bit of sugar in it.

Let the beer sit for a few more days and pull another sample and measure it. Pull one a day later. See if they are the same or if the gravity is still dropping.

Don't try to bottle until the samples are the same 2-3 days in a row.

Wow. Out of curiosity I dropped 1/2 ounce of sugar into a quart of water it clocked in at 1.010 when the water alone was at 1.000 of course.

If my math is right, that means that an ounce of sugar per gallon would boost gravity reading by 5 points. I could be thinking about this wrong though.

So I forgot that I still had a thin layer sitting on the yeast cake that didn't have sugar in it. I racked it off and tested again, and the sugar had pushed it about five points, but it was still at 1.025.

I racked the beer back onto the yeast cake and put it some place a little warmer after giving it a good shake up.

If this beer lives it will be a miracle.

5 oz corn sugar in 5 g should raise the gravity by 2.625 points.

-a.

As epilouge to my little nightmare...

I put it back in the fermentor, gave it a shake and let it sit for several more days. It slowly dropped back down to 1.025 and stopped.

I bottled and it carbed up just fine.

After diagnosing my system and talking to some local professional brewers, I found out that mashing at 158 seemed high to the people I talked to. One professional brewer said that mashing at that temp would turn my grist into hard to ferment sugars that probably wouldn't convert. He suggested mashing at 155 or less to make sure I hit my FG.

At any rate, the beer is low alcohol and sweet with a nice mouthfeel and no bottle bombs. Thanks for all of the advice, and if you've had similar problems, try lowering your mash temp.