Low Gravity!

[Xander]

I've just done a BIAB - About 5.8 Kgs of grain in total. Pre Boil Volume was 30L (calculated by Beersmith)

My gravity is about 1.042. It should be 1.062!!!!

Any ideas on how I can fix this, or am I going to have to throw it away?

I've done a very similar recipe before with no drams. No idea what I have done wrong.

 

[Lord Raja Goomba I]

Don't have to throw it away.

Either boil it down (I'm assuming you're pre-pitch) or adjust your beer expectations to a midstrength. It'll be beer, just not what you had originally planned.

For the future, it's probably worth figuring out where the inefficiencies lie. I'm not sure, without more info what that will be.

 

[Xander]

Won't boiling it down ruin the hop schedule???

 

[Rocker1986]

Adding extract would increase the gravity.

No need to throw it away. But, which gravity reading are you referring to? I'm assuming the post boil one.

Did any part of your process change between the last one that was fine and this one? Was the pre-boil gravity on target with the Beersmith prediction?

 

[Xander]

Yes, post boil.

The temperature was around the 69 mark when mashing also... may have got a bit hotter (71-72) when bringing the temp back up...

 

[Rocker1986]

I wouldn't think that would cause the gravity to be that far below what you expected though. Do you mill your grain or have it done by the LHBS?

 

[Xander]

Yep, Had the LHBS do it. I can't imagine it was their fault - they have never let me down, and have a great rep.

 

[Rocker1986]

Yeah, I'm not sure the crush would affect it that badly. Plus if it's the same as it's always been it shouldn't be an issue. I'm guessing the sample wasn't at some ridiculously high temperature when you took the reading (just eliminating obvious causes first). How long was it mashed for?

I'm a bit out of ideas. I had efficiency problems recently that I have resolved by moving to a coarser grain crush (out of necessity really trying to get it through the mill when I had the issues with the rollers), stirring the mash regularly, and discovering my hydrometer reads 2 points lower than the real SG (even without this my numbers have improved from the other two changes). But yeah, when it was down, it was consistently down, I didn't have a string of expected outcomes and then suddenly a really low one. :unsure:

 

[Lord Raja Goomba I]

Won't boiling it down ruin the hop schedule???

If the hops have been removed, it won't have a major effect especially if you have a 'non hoppy' beer. If it's hoppy, you will lose some aroma, but again, it'll be a case of the isomerisation will stop, but aroma may suffer. The flip side is that if you're 20 points under, your hop schedule will be severely out of kilter at any rate.

I forgot to ask about that, so my fault, I was a few beers in last night.

 

[Blind Dog]

If you post your recipe, mash schedule (temps and time), volumes (pre and post boil), mash pH (if known), etc. you might get more specific answers. Bit hard to suggest much without knowing more info - the more, the better.

At worst you've made a weaker beer than intended. Quick fix (as already suggested) is adding some extract to up the gravity. That only fixes the symptom though, not the cause.

 

[Xander]

Yeah, I'm not sure the crush would affect it that badly. Plus if it's the same as it's always been it shouldn't be an issue. I'm guessing the sample wasn't at some ridiculously high temperature when you took the reading (just eliminating obvious causes first). How long was it mashed for?

I'm a bit out of ideas. I had efficiency problems recently that I have resolved by moving to a coarser grain crush (out of necessity really trying to get it through the mill when I had the issues with the rollers), stirring the mash regularly, and discovering my hydrometer reads 2 points lower than the real SG (even without this my numbers have improved from the other two changes). But yeah, when it was down, it was consistently down, I didn't have a string of expected outcomes and then suddenly a really low one. :unsure:

Cheers Rocker. The wort temp when I checked it was 30 degrees. I can't imagine that being too hot for an accurate reading??? It did cross my mind though.
It was mashed for 1 hour, with temps between 66-72.

 

[Lord Raja Goomba I]

Google temp correction SG reading. pop in your figures and you'll get an accurate reading. It'll likely only be about 2 points but worth knowing where to find it in future.

 

[Rocker1986]

Yeah, it would read around 2 points low if it's 30C and the hydrometer is calibrated to 20C, but certainly not 20 points low! I have an app on my phone called Convert Everything, which has a temp correction thing in it for SG readings. I find it very useful on brew days because I often can't be arsed trying to get the sample down to exactly 20C.

It sounds like everything process-wise was fine so I'm not sure what's caused this. Perhaps others will have an idea. The only other thing I can think of is that your hydrometer took on liquid causing it to sink further into the wort and giving a false low reading, but that's pretty unlikely.

 

[jibba02]

What brand is the base malt?

 

[Xander]

It was Briess 2 row.

I checked the hydrometer in plain water and it sat on 1.000 so I'm guessing that is fine?

I did leave the lid on for about half the boil - would the condensation going back into the wort throw my Gravity out???

 

[Rocker1986]

Hydrometer sounds fine.

Leaving the lid on during the boil is a huge no-no though. It may throw the gravity out since the steam can't escape and ends up back in the wort, but the bigger problem is that the DMS (or its pre-cursor) gets trapped in there instead of being allowed to boil off into the atmosphere. This can lead to some shitty flavours in the finished beer, like cooked corn/vegetables.

I don't even have the lid on while bringing it up to the boil, although you probably could get away with this if it is removed once it begins boiling or just before this. You don't want the lid on while it's boiling, and definitely not for half the boil! :blink:

 

[jibba02]

hmmm. Well i had 2 sacks of JW Traditional ale and 1 x sack of JW Pilsner and all the malt gives very bad efficiency. so far i have used this malt in 9 beers and first wort running's are 20 points low every single time!!! I have given up on JW malt and only use what i have left to make wort for starters. I now use Weyermann for most of my base malts and hit my first wort runnings every single time. 3:1 ratio gives me 1.085

 

[Rocker1986]

Wonder if it's a bad batch? I used JW Trad ale malt about 3 years ago and had no efficiency problems with it. Now I use Fawcett's MO for my ales and Wey Pils or Bo Pils for my lagers. Now that I've sorted out my system (again), I'm consistently hitting 75-76% total efficiency, which I'm happy with.

The lid on for half the boil will have messed up the boil off rate though, so that wouldn't exactly help in achieving the desired gravity. I don't think that in itself would cause it to be 20 points low given that the gravity generally doesn't increase by that much in a standard boil situation (mine usually increase by about 7-8 points over a 75 min boil), but it would have contributed to some of it.

 

[jibba02]

I would say it's a bad batch of barley rather than a bad malting process. It was a very frustrating experience trying to fix problems that didn't exist. When all along it was the shit malt

 

[Xander]

Thanks for the feedback gents!

I've learnt a few things here. I'm pretty sure it was my own fault - leaving the lid on the boil. I'm confident the LHBS have quality malt, as it is frequently turned over. I'm still pretty new to this so I have to put my hand up and take the blame!

Pretty annoying though, as the clarity at this stage is much better than I have achieved previously. I've got 1kg of Light Dry Malt extract, so I will put that in the batch tonight and pitch the yeast. Hopefully it doesn't effect the flavour too much and turns out ok!

Will get another batch going soon anyway! Need to get the dark beers ready for winter!


Cheers
:beer: