Can't figure it out

[psujeeperman02]

Brewed an east coast IPA last month.
I hit my OG of 1.042.
I then let the yeast do its magic for about 2 weeks and dry hopped.
Recipe in beersmith says my FG should be about 1.015.
My FG was 1.020.
What happened?
Did I not let it fermenter out?
Temp was about 64-67*F during fermentation for London lll.

Not complaining about. 5.5% abv IPA, but was hoping for a bit more and was definitely hoping to match the beersmith calculations.

 

[JONNYROTTEN]

Theres only a few things that effect FG:

Grain crush off
Water volume off
Mash temp off
underpitching yeast

A couple points off is ok in my book. 5 points is to much

 

[day_trippr]

If the OG was as predicted then crush and volumes are out of the picture.
That leaves the yeast and the mash temperature...

Cheers!

 

[TheMadKing]

Brewed an east coast IPA last month.
I hit my OG of 1.042.
I then let the yeast do its magic for about 2 weeks and dry hopped.
Recipe in beersmith says my FG should be about 1.015.
My FG was 1.020.
What happened?
Did I not let it fermenter out?
Temp was about 64-67*F during fermentation for London lll.

Not complaining about. 5.5% abv IPA, but was hoping for a bit more and was definitely hoping to match the beersmith calculations.

That's only 2.9% ABV not 5.5%. It's also only 51% attenuation, so something is wrong with your recipe or process.

Was this an extract recipe?

 

[McKnuckle]

Were both of those gravity measurements done with a hydrometer, or with a refractometer? If the latter, did you compensate for the alcohol in the fermented beer?

 

[myndflyte]

What was your recipe and mash temp?

 

[FVillatoro]

I'd look at:

Mash temp: Make sure you're using a good and accurate thermometer that's been tested for accuracy.

Yeast: If you didn't make a starter before hand, you may experience lower than expected F.G. - also check the viability of it. Pitched enough?

Oxygenation: did you get enough oxygen for a healthy fermentation?

Measuring gravity: are you using a quality (and tested & calibrated) hydrometer? If using a refractometer (check for accuracy too) - use a final gravity calculator because the brix will be off with fermented beer.

 

[psujeeperman02]

I've been contemplating over this one for the last few days...I'm thinking the issue may have been with yeast. It was a 10gal batch and I bought two yeast smack packs which I then combined to make a starter.
I used 4 cups water with 1 cup DME.
Does that sound about right?

 

[TheMadKing]

I've been contemplating over this one for the last few days...I'm thinking the issue may have been with yeast. It was a 10gal batch and I bought two yeast smack packs which I then combined to make a starter.
I used 4 cups water with 1 cup DME.
Does that sound about right?

No, you most likely did not get any cell multiplication and damaged your yeast.

I'm estimating 1 cup of DME to be about 250g and 4 cups is about 0.975 liters. That results in a gravity of 1.090.

Your starter should be 1.038 to 1.040.

Your ratio should be 1L and 100g of DME, 2L and 200g DME etc.. 10 to 1 ratio of water to dme.

A 1L starter also barely results in any cell multiplication for a single smack pack, so you should have at minimum 4L

 

[FVillatoro]

I've been contemplating over this one for the last few days...I'm thinking the issue may have been with yeast. It was a 10gal batch and I bought two yeast smack packs which I then combined to make a starter.
I used 4 cups water with 1 cup DME.
Does that sound about right?

There's 8 ounces in a cup, so:

4 cups = 32 oz (1/4 gallon).
1 Cup of DME = 8oz

So that would yield a started OG of 1.084 which is very unhealthy for the yeast - with such high gravity you stressed the yeast before you ever pitched it in the beers.

I would have used 0.7 of a gallon (90 oz)

90oz with 8oz of DME = 1.030 OG

You should aim for starters in the 1.030-1.040 range.

I start at 1.030 and after boiling for 12-15 mins it goes to 1.035ish or so.

 

[psujeeperman02]

There's 8 ounces in a cup, so:

4 cups = 32 oz (1/4 gallon).
1 Cup of DME = 8oz

So that would yield a started OG of 1.084 which is very unhealthy for the yeast - with such high gravity you stressed the yeast before you ever pitched it in the beers.

I would have used 0.7 of a gallon (90 oz)

90oz with 8oz of DME = 1.030 OG

You should aim for starters in the 1.030-1.040 range.

I start at 1.030 and after boiling for 12-15 mins it goes to 1.035ish or so.

Sounds like I would have been better off just pitching the smack pack without a starter :-/
Well, 'twas a learning experience.

Also, where do the OG numbers come from? How do you know that 1 cup of DME with 4 cups of water yields a starter of 1.084?

Knowing this info will surely help for my next brew.

 

[day_trippr]

fwiw, there's some SWAG involved when using volume measurements for the DME, better to use a scale.

There are lots of on-line calculators for pitch rates and starter construction.
This one is fairly user friendly...

Cheers!

 

[TheMadKing]

Sounds like I would have been better off just pitching the smack pack without a starter :-/
Well, 'twas a learning experience.

Also, where do the OG numbers come from? How do you know that 1 cup of DME with 4 cups of water yields a starter of 1.084?

Knowing this info will surely help for my next brew.

Its a points per pound per gallon calculation.

I plugged it into brewers friend's online recipe calculator. I set the recipe to .975L and estimated the weight based on a cup of table sugar.

10 parts water to 1 part DME will get you there every time.

 

[RM-MN]

Sounds like I would have been better off just pitching the smack pack without a starter :-/
Well, 'twas a learning experience.

Also, where do the OG numbers come from? How do you know that 1 cup of DME with 4 cups of water yields a starter of 1.084?

Knowing this info will surely help for my next brew.

You need a certain (within a wide range) amount of yeast to be able to brew the best beer. Where you grow the yeast is up to you. In the past yeast viability was poorer and a starter would make sure you had viable yeast. Now yeast is usually assumed to be viable but many still use a starter to be sure they have sufficient yeast right into the fermenter but I believe that you can pitch just a single package directly into your wort...but you have to be sure you have the conditions to grow the yeast there. Yeast needs oxygen to grow more cells so aeration becomes more important with a smaller amount of yeast. Aerate well and your yeast will multiply. Take a peek at this exbeerimnet's results.

http://brulosophy.com/2015/04/20/yeast-pitch-rate-single-vial-vs-yeast-starter-exbeeriment-results/