Very low pre boil gravity. Can I save this brew?

[AdamJohn]

I am currently in the boil process for my first Mini BIAB. However it isn't going to plan.
My Gravity into boil was predicted to be 1.027/8 but I have achieved 1.013. It was a 90 minute mash at 66c. I dropped to 65 by the end of the mash.

Put the kettle onto boil and as it was coming to a boil took the OG which was 1.013.

Any ideas on what has gone wrong are appreciated :-) And is there anything I could do to save this brew? Off the top of my head I can only think of adding some sugar? DME would require a trip the the HBS which is shut at the moment.

It is for 9L into the FV

Brewer:
Style: Bitter
Source Recipe Link:
ABV: 4.1% (assumes any priming sugar used is diluted.)

Original Gravity (OG): 1.04
IBU's (Tinseth): 31.2
Bitterness to Gravity Ratio: 0.78
Colour: 12.2 EBC = 6.2 SRM

Note: This is a Pure BIAB (Full Volume Mash)

Times and Temperatures

Mash: 90 mins at 66 C = 150.8 F
Boil: 90 min
Ferment: 14 days at 18 C = 64.4 F

Volumes & Gravities
(Note that VAW below is the Volume at Flame-Out (VFO) less shrinkage.)
The, "Clear Brewing Terminology," thread at http://www.biabrewer.info/

Total Water Needed (TWN): 15.32 L = 4.05 G
Volume into Boil (VIB): 14.93 L = 3.94 G @ 1.028
Volume of Ambient Wort (VAW): 9.99 L = 2.64 G @ 1.04
Volume into Fermentor (VIF): 9 L = 2.38 G @ 1.04
Volume into Packaging (VIP): 8.33 L = 2.2 G @ 1.008 assuming apparent attenuation of 80 %

The Grain Bill (Also includes extracts, sugars and adjuncts)

Note: If extracts, sugars or adjuncts are not followed by an exclamation mark, go to http://www.biabrewer.info (needs link)

95.1% pale malt (5 EBC = 2.5 SRM) 1473 grams = 3.25 pounds
4.9% crystal malt (150 EBC = 76.1 SRM) 75 grams = 0.17 pounds

The Hop Bill (Based on Tinseth Formula)

31.2 IBU Golding Flowers (5.26%AA) 21.9 grams = 0.773 ounces at 90 mins
0 IBU Fuggle Flowers (5.21%AA) 4 grams = 0.14 ounces at 0.1 mins

 

[Rivvo]

Give it a good stir and check again, sometimes you can get a false reading as the heavier particles sink to the bottom, alternatively check after the boil and if it's still low add some honey, sugar, lme etc until you have the desired gravity.
I would always mash out myself raising the temperature to about 76' over 10 minutes or so to get the most of the remaining sugars out.

 

[AdamJohn]

Thanks for the quick response Rivvo. I'll do just that, it's all a learning curve! I have been reading a lot during the 90 mins of the boil and have identified a couple of things which could contribute to the low OG. :thumb:

One being the grain. Bought from my LHBS, pre crushed in 1kg bags with some sticky tape round the top (not sealed). I have no idea how long they have been sitting around on the shelf.

Possibly my bag isn't brilliant. It is slightly tapered towards the bottom so it doesn't line around the bottom of the pan. This could restrict the grain during the mash.

I'm sure there are others as well.

I'll try the mash out on the next go (with the remaining grain I have) and see if that helps. I'll order grain from Malt Miller next time and repeat the process to see if that helps

 

[Rivvo]

Good, let me know how the gravity ends up, don't forget to add the grain to the water not water to the grain and stir as you do so, I'm unsure that the shape of the bag is that important so long as it's big enough. Good luck.

And yes the Malt Miller is excellent for service and goods, in my experience.

Ps
If you need any further help you could try posting on the craft brewing forum, you don't have to join and it's free and ad free!

 

[AdamJohn]

Thanks again Rivvo. You originally mentioned about giving it a good stir, but unfortunately I was already in the boil so unable to do so. Had I done that I don't think I would have been so worried!

I have just done a post boil ready at obtained 1.037. So although a bit low than the desired 1040 it is much nearer the desired gravity.

 

[airymary]

If your hydrometer is calibrated at 15 or 20c, readings at higher temps will be inaccurate. Check the temp when you take the reading, and use the correction calculator on the calculators page linked above.

Cheers,
Chris

 

[Rivvo]

Nice one, and Chris says don't forget to temperature adjust or let the sample cool.
I would also advocate rehydrating your yeast (if you don't already do that) whilst the wort is cooling.

 

[AdamJohn]

Hi guys,

I had cooled the sample to 25 then put the result through the calculator. So it should have been accurate.

Just using dried yeast, going to put half a packet of s-04 in, saving the rest for a future brew. I think it should keep if in the fridge for a few weeks.

 

[Fil]

If you use just 1/2 a pack of dry yeast you risk underpitching, if you want to save some yeast for another brew, feed it in a starter for a few days in advance before splitting in 2 using 1/2 and keeping 1/2 in the fridge dormant till your next brew.

next time you can boil a little longer if your gravity is low, evaporate off more leaving you with a more concentrated higher gravity liquor.

 

[Rivvo]

If you use just 1/2 a pack of dry yeast you risk underpitching, if you want to save some yeast for another brew, feed it in a starter for a few days in advance before splitting in 2 using 1/2 and keeping 1/2 in the fridge dormant till your next brew.

next time you can boil a little longer if your gravity is low, evaporate off more leaving you with a more concentrated higher gravity liquor.

+ 1 to the above, for the sake of a couple of quid it really isn't worth only using half a pack, particularly as when pitching dry you kill something like 50% of the cells!

 

[AdamJohn]

Ah, good to know for next time.

I had thought there would be a risk of over pitching as the instructions on the packet said it was good for 20 to 30 litres. As my batch was only 9l I thought half should do the job.

Would it be a good idea to make a starter with the remaining yeast for the next brew (similar sized batch)?

 

[Fil]

Ah, good to know for next time.

I had thought there would be a risk of over pitching as the instructions on the packet said it was good for 20 to 30 litres. As my batch was only 9l I thought half should do the job.

Would it be a good idea to make a starter with the remaining yeast for the next brew (similar sized batch)?

Sorry Adam.. i didnt read properly with a 9l volume 1/2 a 5 gallon targeted pack will be fine Whoops!!!!

while most dry yeast packs produced these days and used within date can be dry pitched no problems (when pitched at the right sort of rate) if its an opened pack (top rolled closed with a cloths peg to secure in the fridge) i would hydrate, ideally 100g of dme to each litre in proportion will give u a hydrating liqour with a gravity circa 1040.. (tho 5-6 t-spoons of sugar in a mugs worth works too)