low OG on first Partial Mash

[TacoGuthrie]

Tried out my first PM tonight. Everything went really well all the way through, I thought. I used a 3G "Bubba Keg" w/ spout as a mash tun and it worked well. Once I had my mash temp at 154 it only dropped to 149-150 after an hour.

Like I said everythinge went smooth all the way through. Then I took my gravity reading and it came out at 1.030!!

I've been reviewing it and it looks like I mixed up a bit and came up almost a lb short on my LME addition. However I ran that through BeerSmith and that should only account for a couple gravity pts.

Here is the recipe I used. It's basically a PM of BM's Nierra Sevada, but I had to fiddle with hops because of my low AA Perle.

Style: American Pale Ale
TYPE: Partial Mash
Taste: (35.0)

Recipe Specifications
--------------------------
Batch Size: 5.00 gal
Boil Size: 3.25 gal
Estimated OG: 1.041 SG
Estimated Color: 5.8 SRM
Estimated IBU: 39.8 IBU
Brewhouse Efficiency: 75.00 %
Boil Time: 60 Minutes

Ingredients:
------------
Amount Item Type % or IBU
2.00 lb Pilsner Liquid Extract (3.5 SRM) Extract 28.57 %
4.00 lb Pale Malt (2 Row) US (2.0 SRM) Grain 57.14 %
0.50 lb Cara-Pils/Dextrine (2.0 SRM) Grain 7.14 %
0.50 lb Caramel/Crystal Malt - 40L (40.0 SRM) Grain 7.14 %
2.00 oz Pearle [4.70 %] (60 min) Hops 28.7 IBU
0.50 oz Cascade [6.90 %] (15 min) Hops 5.2 IBU
0.50 oz Cascade [6.90 %] (10 min) Hops 3.8 IBU
0.50 oz Cascade [6.90 %] (5 min) Hops 2.1 IBU
0.50 tsp Irish Moss (Boil 10.0 min) Misc
1 Pkgs S-05 (Safale) Yeast-Ale

Can anyone help me out?? Where did I go wrong?

 

[kenche]

When I was doing partial mashes I often had problems hitting my target gravities. My solution was to have extra extract on hand to make up for any shortcomings of the partial mash.

I would take a gravity reading of the wort from the partial mash, and compare it to the recipes target gravity and then determine how much extract to add.

There are some more details in this thread.

 

[size]

^Agreed. Sometimes there are unforeseeable variations in your brews (i.e. quality of grains, how fine they're ground, etc).

 

[Cheeto]

I am not going to assume anything here and i am just going to ask.

Did you sparge?
What temp was the sparge water?
When did you add the LME?
The only other thing is could be is an improper mixing of the wort and top-off water

Give it a few weeks and test the gravity again !

you might find those missing points

-Jason

 

[Yooper]

Is that correct? 4 pounds of two-row, and 2 pounds of LME? For a PM, that is really a pretty low amount of LME with only four pounds of 2-row.

Even with me doing AG, I often get efficiency of around 70% or so. If I was doing that recipe, that best I could hope for is about 1.035. If you got 1.030, then you did ok with the PM. Probably about 60% efficiency, which will improve when you get your process down.

At 70% efficiency, 4 pounds of two-row would give you about 20 gravity points.

 

[TacoGuthrie]

I am not going to assume anything here and i am just going to ask.

Did you sparge?
What temp was the sparge water?
When did you add the LME?
The only other thing is could be is an improper mixing of the wort and top-off water

Give it a few weeks and test the gravity again !

you might find those missing points

-Jason

Batch Sparged 7 quarts at 180. Let it sit for 5-10 mins before collecting the second runnings.

Added LME with about10 mins left about the same time as the wort chiller. I stopped the timer and let it come back to a boil for the last 10 mins.

I've made that error before of improper mixing with top off water. I shook the helloutta that thing. Even drove it across town and took another reading (I was brewing at a friend's house.

 

[TacoGuthrie]

Is that correct? 4 pounds of two-row, and 2 pounds of LME? For a PM, that is really a pretty low amount of LME with only four pounds of 2-row.

Even with me doing AG, I often get efficiency of around 70% or so. If I was doing that recipe, that best I could hope for is about 1.035. If you got 1.030, then you did ok with the PM. Probably about 60% efficiency, which will improve when you get your process down.

At 70% efficiency, 4 pounds of two-row would give you about 20 gravity points.

This is what I think might have happened.

Original recipe calls for 7.5 lbs of 2row. I was going to do 5lbs or 2 row and about 2lbs of LME to hit that. Then at the last minute I decided to back off down to 4lbs for fear my mash tun/Bubba Keg couldn't hold that much grain with Carapils and Crystal as well.

However my downfall was to not increase the amount of LME back up to what I needed. Although really I was short less than a lb. I needed to replace 3.5 lbs of grain with 2.625 (or around that) of LME.

It was a supposed to be a session beer, right

 

[Donner]

A question. Did you measure how much you collected from your mash? I am wondering if your extraction/ collection was a touch low and maybe you topped up to 5 gallons and diluted your gravity. Or it could be a combination of several things.

 

[TacoGuthrie]

I added my first runoff to 2 quarts of boiling water, after my second runoff collections I was exactly at 12L mark on my brew pot. Gave me a boil volume of a little more than 3G.

How much does a fine grind affect this kind of thing? I'm no expert but I think my LHBS grinds our grain pretty fine. There is always powder in the bottom of the bag.

 

[CobraAgent]

The same thing happened to me the weekend. My first partial mash and og was 1.030. I used 4 lbs total of speciality grains 1lb of lme. I freaked and called my lhs and walked him through what i did. My error was simple (though it is something you seemed to get right). I was told to bring my water up to 175 then add my grains this should bring it down to 155. It didnt mine sat for an hour and barly got down to 155. It only sat for an 30 min at 155. Lhs told me to check my gravity in a week and might have to add some sugar to get my back up. He told me that I could still end up with a great been but low alcohol content.

 

[TacoGuthrie]

I just checked my primary. No fermentation yet but i'm not worried.

I'll leave it for a week, take another gravity reading. I'm just trying to get to the bottom of why?

I've run #s through beersmith. Even with only 2lbs of LME and 60% efficiency I should be around 1.036 not (a generous) 1.030.