Low OG and Low FG

[revelation]

Ok, rather than revive a necro thread, I decided to post a new one. My last four batches have all come in about 0.10 to low on OG and typically low on FG. I tested my hydrometer and it came it at 0.998 at room temp (76 degrees F), so I don't think it is that. These are both AG and extract brews. This has occurred only since June, before I was spot on with both AG and extract.

My first low brew was a Summer Stout (tastes awesome):

5# Pale 2 Row
5# Munich dark 20L
1# flaked oats
0.5# Crystal 60
0.5# Carafa III
0.5# Roasted Barley
0.5# Chocolate

60 minute single infusiuon at 154 F but the mash temp was a bit all over the place due to a broken thermometer, which likely caused the error.
Supposed to be 1.061 and ended up at 1.048
FG supposed to be 1.015 and ended at 1.014

Black Ale:

9# pale 2 row
0.5# Crystal 120
0.5# Carafa III

60 minute single infusion at 148 F
Supposed to be 1.050 but OG was 1.042
FG supposed to be 1.012 but ended at 1.004

Did an extract that was supposed to be 1.042 and ended at 1.032 (which had happened before and suspect is improper mixing of boil and extra water).

Saison

9# German pilsner
1# Wheat

60 minute single infusion at 153 f
Supposed to be 1.052 and was 1.042
FG was supposed to be 1.016 and ended up at 1.002

I'm just not sure what is going on. My previous batches before this summer were like clockwork in hitting OG and FG. Mayhaps the cooling temps? Even with the correction for the warmer than normal, I am still way off...

 

[hercher]

First off, have you changed any part of your process? Are you sparging exactly the same as you did before? How about the grain crush? Did you change suppliers? Any changes to your water that might require some pH adjustments? Are you stirring your mash properly to ensure there are no clumps and the temperature is evenly distributed?

As for your FG, are you pitching the same amount of yeast, or did you dramatically increase your pitch rate? (BTW, I would expect your Saison to finish quite a bit lower than 1.016.) Again, any changes in your process.

The key is: if you were hitting your predictions spot on before June, something must have changed. You need to figure out what is different.

 

[WoodlandBrew]

Agreed. A low OG is typically sparge related, but can be the crush and a number of other factors. There is a post on my blog about maximizing efficiency that might help. My book has a nice table for this (which will be published next month)

A higher than expected attenuation could be over pitching as the previous poster mentioned. It could also be mash temperature. Search my blog for "Mash Temperature" and the posts should come up.

 

[revelation]

First off, have you changed any part of your process? Are you sparging exactly the same as you did before? How about the grain crush? Did you change suppliers? Any changes to your water that might require some pH adjustments? Are you stirring your mash properly to ensure there are no clumps and the temperature is evenly distributed?

That is the thing, I used the same LHBS and followed the same procedures. The only big difference has been my cooling times due to warmer weather and the warmer water. I have a cooling coil and it takes more time because the temp differential between the tap water and the wort is less.

As for your FG, are you pitching the same amount of yeast, or did you dramatically increase your pitch rate? (BTW, I would expect your Saison to finish quite a bit lower than 1.016.) Again, any changes in your process.

The key is: if you were hitting your predictions spot on before June, something must have changed. You need to figure out what is different.

Used the same yeast as always - usually one packet of dry safale US-05 or US-04 (although for the Saison I used Whitelabs 565).

I'm racking my brain for something that I'm doing differently and cannot think of it.

Thanks for your reply, I'm definitely puzzled.

 

[pumpkinman2012]

as soon as I tightened up my grain mill just a bit, with the finer crush, I've been hitting my numbers every time.

 

[chickypad]

Adding to the above questions, have you changed the way you are measuring your volumes? Is the LHBS crushing for you? Maybe they loosened up their gap.

 

[hercher]

It's perplexing, to be sure. Monitor the pH of your mash carefully and make sure you are right around 5.2. As the posters above suggested, perhaps it is your crush. If your LHBS is milling your grain, ask them if they changed the setting. You might also want to calibrate all of your equipment -- thermometers, hydrometers, pH meters.

 

[revelation]

Thanks all. I just received a MM2 for my bday, so I'll be able to monitor the crush better. I'll work on the pH side and check my thermometers.

Most likely my next batch will be spot on and it will remain a mystery. I do suspect that the crush from the LHBS is the variable. It is a self serve couple of mills and with all the people using it, the gap widens...

 

[revelation]

Update: Must have been the crush because hit my numbers in my latest batch with my own mill. Made sure to have a good crush.