Low Final Gravity

[devin81knez]

I just finished two small batches .8 gallons and .6 gallons and i noticed on both of them my final gravity was lower than the brew calculator predicted.
Recipe as follows

Est og 1.057 (i was spot on)
Est FG 1.016( I had 1.006)
Boil vol- 1.2 gallons
Batch vol- .8 gallons

1 lb light DME
.125 lb American Crystal 20l
.06LB chocolate
.06 LB Biscuit
.06 LB carapils
I dont think hops are necessary to list

yeast Safale 05 - 5 grams

What are some possible reasons as to why i has such a low FG?

I did not see any signs of contamination and the beer tastes fine but it has weak body and higher alcohol. I used a refractometer to calculate Gravities. this also happened on my .6 batch which turned out almost the same on gravity points 1.053-1.006

HELP!!

 

[sfgoat]

Looks like you may have over pitched a little.

 

[Hex23]

My bet is on inaccuracy in the process of correcting FG readings from the refractometer. Obviously you may not want to take a hydro sample from batches that small. But correcting FG's based on OG is known to not be that accurate.

But if your tastes tell you it is a lower FG, then maybe it is. I agree, that's probably almost a 2x over-pitch of dry yeast. But I believe over-pitching often leads to under-attenuation.

 

[devin81knez]

Original brix was 14

Final brix was 7
My refractomater is suppose to correct for temperature and i make sure its calibrated before every use.

 

[Hex23]

So when I plug those numbers in to Beersmith, it says FG = 1.010. It just goes to show that there is inaccuracy and disgreement in that method.

 

[devin81knez]

I just realized my original gravity on the first brew was 1.01.. Looked at the wrong note so i guess whatever calculator i have is similar to beersmith. Now i would think an attenuation of 82% isnt impossible but what could i do in the future to get closer to my est. FG?

Thanks for the quick answers you have eased my mind not sure if i would sleep without them.

Cheers

 

[devin81knez]

I just realized my original gravity on the first brew was 1.01.. Looked at the wrong note so i guess whatever calculator i have is similar to beersmith. Now i would think an attenuation of 82% isnt impossible but what could i do in the future to get closer to my est. FG?

Thanks for the quick answers you have eased my mind not sure if i would sleep without them.

Cheers

I meant fg of 1.01

 

[Hex23]

Trying to get a beer to not over-attenuate can be more challenging than getting it to not under-attenuate.

Some of the things you might be tempted to do will cause other problems, like
- Monitoring the FG and taking measures to stop fermentation early
- Skipping aeration
- Underpitching, not rehydrating, etc

Some other more promising avenues:
- With AG, mash higher (though your use of DME is unlikely the cause of high attenuation)
- Use more ingredients with less fermentability (crystal malts, etc)
- Try to keep ferm temperatures on the cool side (good idea anyway)
- Pick a yeast with lower attenuation

Still, I'm suspicious of the use of the refractometer to measure FG. If you can stand to pull a hydrometer sample, I'm betting it's not really 1.010