OG lower than expected

Hi all.
I brewed an All Grain batch of a German Pilsner last night and everything seemed to be going well until right before I added my Yeast starter into the primary fermenter.
My estimated OG was 1.045
My measured OG was actually 1.031??

I am posting the recipe along with any other steps in hopes of finding out where I may have gone wrong.
I use Beersmith to create my recipes and it gives me a 72% efficiency.

1.00 tbsp PH 5.2 Stabilizer (Mash 60.0 mins)
0.50 g Gypsum (Mash 60.0 mins)
7 lbs 9.6 oz Pilsner (Weyermann) (1.7 SRM)
8.6 oz Carapils (Hoepfner) (2.0 SRM)
5.5 oz Munich II (Weyermann) (8.5 SRM)
0.8 oz Crystal, Medium (Simpsons) (55.0 SRM)
1.07 oz Saaz [6.40 %] - Boil 60.0 min
0.36 oz Saaz [6.40 %] - Boil 30.0 min
1.00 Items Whirlfloc Tablet (Boil 15.0 mins)
0.43 oz Hallertauer [4.70 %] - Boil 15.0 min
0.45 oz Hallertauer [4.70 %] - Boil 5.0 min
2.0 ltr Yeast Starter of Czech Budejovice Lager (White Labs #WLP802) with most of the wort decanted and at room temp for at least 2 hours prior to putting it into the fermenter.

Here’s a list of my equipment:
5 Gallon Stainless Steel Pot
10 Gallon Igloo Cooler Mash Tun
50’ RibCage style Wort Chiller (added 10 minutes before end of boil)
Barley Crusher Malt Mill (only used 4 times)

Steps:
Single Infusion, Light Body, Batch Sparge
Mashed at 148F for 75 minutes and did a batch sparge at a slightly higher temp
Mash In: Added 2.92 gal of water at 161.9F = 148.0F for 75 minutes
Sparge: Batch sparge with 2 steps (0.45 gal, 2.35 gal) of 168.oF water.
Vorlaufed all the wort and proceeded to my 2 step sparge (where I mixed the grain in between each session. I also would vorlauf 5 times with each step).

I ended up with a total of 4.44 Gallons of wort to boil.
After the boil, once chilled and in the fermenter I added 2 Gallons of Water (per Beersmith’s instructions) to make a total of 5.5 Gallons.
I then mixed the wort for a while in order to oxygenate it as best as I could.
After that, I proceeded to get a reading for my O.G and found out that it was only at 1.031
My house was at 72.0F

I am really not sure what could’ve gone wrong.
Would it be o.k. to make a small batch of just Pils Malt and add it into the primary even though almost 24 hours have gone by?
Any help would be very appreciated.
Thank you in advance.

 

Your efficiency was lower than the default 72%, which could be caused by any number of things. The first thing to check is your crush: is you mill adjusted properly?

Also, in the future, you can measure the gravity of the wort post-boil, then add water to adjust down to target. If you had added less than 2 gal of water you could've still hit your target gravity (albeit at a slightly lower volume)


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Thank you! I will definitely check. Getting myself a Blade Master Feeler Gauge as well.
In the meantime, any advice on how to salvage this batch? Or should I just wait and see what the outcome will be?
Thanks again.

 

Just wait and see, should still be a drinkable (however "light") beer


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You must have been at around 3.43 gallons of cooled wort which included the trub. Your gravity was probably at 1.050, because I ran it through a dilution calculator with these numbers; 3.43 g of 1.050 to make 5.5 g equals a 1.031 OG.

You needed 2 more pounds of grain to meet that 1.045 OG and as it is, you are under hopped because of a concentrated wort boil.

You must have BS set at zero trub loss. Setting it to zero gives a lower grain bill.

To make this recipe again you would need a 10 gallon boil pot, 10.35 pounds of grain and 2.31 ounces of hops of which produces about 1 gallon of trub. You would have 5.5 gallons in the fermentor with no dilutions.

Making this again from the same pot would be difficult, more grain, double the hops and double the trub, etc.

Hope this helps.

 

Wow!! Thanks guys!
I just got schooled big time... and have never felt better.
I will definitely make these adjustments.
As far as trub loss I did have it at 0.75 but that may have been too little.
Here is my equipment profile on BeerSmith:
My Equipment
Batch Volume: 5.00 gal
Efficiency: 72.0 %
Hop Util (Large Batch): 100.0 %
Mash/Lauter Tun
Mash Tun Volume: 10.00 gal
Mash Tun Mass: 9 lb
Tun Specific Heat: 0.30 Cal/g-C
Lauter Deadspace: 0.25 gal
Adjust Vol for Deadspace: Yes
Boiler Kettle Top up: 0.00 gal
Calc Boil Vol: Yes
Boil Volume: 4.44 gal
Boil Time: 60 min
Boil Off: 0.54 gal
Post Boil Vol: 3.90 gal
Cooling Loss: 0.16 gal
Fermenter/Bottling Volumes
Trub/Chiller Loss: 0.75 gal
Top Up Water: 2.00 gal
Batch Volume: 5.00 gal
Fermenter Loss: 0.40 gal
Bottling Volume: 4.60 gal

I am in the process of getting a new system built Kal clone of The Electric Brewery for 30 gallons (big family) but feel I still have a long way before I feel comfortable brewing 20 gallons of a mistake. That would be an expensive mistake. I am however looking forward to having better efficiency, etc that this newer system will allow me. You know? Better whipped tools.
Nonetheless, I need to be able to succeed at a smaller scale first.

In the end... I'm still going to continue fermenting this batch. It actually started fermenting fairly quick. Then I'll Lagger it as usual. And who knows?
I may have just created the first Budweiser Ultra Mega Light for the world to enjoy.
Thanks again and please feel free to continue to educate me. Very appreciative.



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Agree. You may want to get a few more successful 5 gal brews under your belt before you invest the time, money & effort in a 30 gal electric system. That's a big investment...