Consistant Low OG, Partials, Need pointers

I am partial mashing, and constantly about a point or more low according to Beersmith.

For instance #1:
-5.5 pounds DME
-5.5 pounds Grains
-5.25 gallon batch
-Beersmith estimate, 60% efficiency 1.065
-Actual 1.052

#2
-3.3 pounds LME
-4 pounds grains
-5.25 gallons batch
-Estimate 60% efficiency 1.039
-Actual 1.032

Setup:
-15 gallon rectangle cooler, fly sparging from a 5 gallon cooler
-CPVC manifold
-I am able to sparge until the wort is almost running clear
-Mash times 90 mins, fairly consistant temps 148 to 152
-Sparge at 168 degrees
-Boiling 4 gallons
-Topping off
-I check my OG at 65 degrees
-The grind is the "house" grind. They are a solid store, so I trust their grind.
-I checked my hydrometer, it reads 1.0 with water.

What am I missing? It's driving me crazy!!!

The first thing I thought of was that you were not milling your grains, but that was wrong.
Next possibility is not mixing any top-up water with the wort. Are you using top-up water? If so, it takes a lot of vigorous stirring to mix it with the wort. If this is the problem, don't worry. The yeast will do the mixing for you, and the only problem would be that you didn't get a correct OG reading.
The last thing that I can think of is the size of the cooler. You would not have much of a grain bed depth in a 15g cooler, which could give you poor lauter efficiency. If this is the case, you may want to try batch sparging, where the grain bed depth isn't as important.

-a.

Next time you brew, check your OG before you add top up water. If you have that and the volume, you should be able to do some quick math to see if it's just your top up water not mixing properly.

Thanks for the replies.

I will check prior to topping off next time. I do shake the s@$t out of it....that had come to my mind as well

How do I properly check efficiency? Can I check it prior to the boil?

I also think that it could be the cooler with the fly sparge. That is a big cooler for not a lot of grain. Off hand that is what I would look at. Maybe a batch sparge would help some

squidbait said:

I am partial mashing, and constantly about a point or more low according to Beersmith.

For instance #1:
-5.5 pounds DME
-5.5 pounds Grains
-5.25 gallon batch
-Beersmith estimate, 60% efficiency 1.065
-Actual 1.052

#2
-3.3 pounds LME
-4 pounds grains
-5.25 gallons batch
-Estimate 60% efficiency 1.039
-Actual 1.032

Setup:
-15 gallon rectangle cooler, fly sparging from a 5 gallon cooler
-CPVC manifold
-I am able to sparge until the wort is almost running clear
-Mash times 90 mins, fairly consistant temps 148 to 152
-Sparge at 168 degrees
-Boiling 4 gallons
-Topping off
-I check my OG at 65 degrees
-The grind is the "house" grind. They are a solid store, so I trust their grind.
-I checked my hydrometer, it reads 1.0 with water.

What am I missing? It's driving me crazy!!!

Click to expand...

since that first one is basically impossible (efficiency of about 20%) and the second isn't much better (about 40%), I'm guessing it's just a poor mix. were these readings taken off the top?

next time I'd check the OG pre- and post-boil.

DME will yield 46 points per pound per gallon.
LME will yield 37 points per pound per gallon.
Both of these will yield 100% efficiency.

Grains yield about 36 points per lb per gallon, but this has to be scaled by your efficiency.

In your first recipe:
-5.5 pounds DME
-5.5 pounds Grains
-5.25 gallon batch
5.5 pounds DME * 46 / 5.25 = 48 points
5.5 pounds grain * 36 * 60% / 5.25 = 23 points.
Add the two amounts together, and you get 71 points, or a gravity of 1.071.

Why is Beersmith different? It is possible that your grains don't yield 36 pppg (some yield a bit more, others a bit less). It also takes dead space into account, and you will probably lose a few points because of this, trub, and hop absorption.

If you check your gravity pre-boil, you will probably have mixing problems unless you stir really well. If you check your gravity post boil, you shouldn't have any mixing problems, and you can calculate the diluted gravity as ((pre-top-up gravity - 1.000) * pre-top-up volume / post-top-up volume) + 1.000
i.e. If you have 3.5 gallons at 1.075 prior to topping up, and you top up with 1.75 gallons water, you will end up with a gravity of ((1.075 - 1.000) * 3.5 / 5.25) + 1.000
= (0.075 * 3.5 / 5.25) + 1.000 = 1.050

-a.

dcp27 said:

since that first one is basically impossible (efficiency of about 20%) and the second isn't much better (about 40%), I'm guessing it's just a poor mix. were these readings taken off the top?

next time I'd check the OG pre- and post-boil.

Click to expand...

My readings are always taken off the top. After I top off, I pick up the carboy and shake for about 30 seconds or so. Then, I use a beer thief (or whatever it's called), and take the mixture from the very top. I then make sure it's cooled to 65 degrees (it's usually at about 75), and take my reading.

I will definetly check pre top-off next time using ajf's calculations.

It is bumming me out, because I feel like I am very thorough in hitting my temps, and measuring. I am looking into going AG, but don't want to have to buy twice the grains. Thanks for the help.

Yup, shaking a carboy for 30 seconds isn't going to mix it up much, and would explain the apparent low gravity.
The good news is that your real gravity will be higher than what you measured.
The bad news is, you won't know how much higher.

-a.

ajf said:

Yup, shaking a carboy for 30 seconds isn't going to mix it up much, and would explain the apparent low gravity.
The good news is that your real gravity will be higher than what you measured.
The bad news is, you won't know how much higher.

-a.

Click to expand...

Hmm, well I guess that is good news. Hopefully that is it. Because I would say 12 of my last 13 brews have all been way low. How do people get it properly mixed? Looks like I need to hit the gym again.

Have you set Beersmith to Partial Mash? If it is set to extract I think it will give you higher OG estimates. Not sure, I'm learning how to use it.