Beersmith Guestinmations

[nicklawmusic]

Hi there,

I'm wondering anyone can help me. I brewed this last night (my own recipe):
http://beersmithrecipes.com/viewrecipe/796174/stout-to-the-lord-batch-no002

After the mash, I collected around 9L of wort of 1.096. My batch sparge collected around 17L of 1.072. I also ran 1 litre through a third time and collected that (though I didn't take a gravity reading of that).

What I don't understand is that my pre-boil gravity was only 1.059 when Beersmith said I should be hitting 1.072.

I added 400g of DME to this recipe to boost the final ABV and also added 400g lactose sugar as per the recipe and got an OG of 1.064.

I've only just moved over from BIAB and don't understand that, using a mash tun and manifold, how my mash efficiency can only be 67% and overall efficiency 64%, when I was hitting between 69-77% doing BIAB.

Any ideas what went wrong and how I can rectify this next time?

Thanks,
Nick

 

[beerme70]

What did you use to test gravity, refractometer or hydrometer? Did you adjust for wort temp? The higher the temp, the lower your reading will be. Some refractometers (I have a brix) will self adjust for this, but I also use a hydrometer at times, and you have to take temp into account. For example, if calibrated your hydrometer at 60* (I'm a yankee, so that's in F, not C) and your hydrometer was reading 1.059 like you stated, and your wort temp was at 125*, your adjusted gravity would be around 1.073. However, if your wort temp after sparging is around 165*, that would put your pre-boil gravity in the neighborhood of 1.085.

 

[nicklawmusic]

I used a hydrometer, but I waited for the samples to cool to 20C.

 

[cyberbrew]

If I was guessing, I would guess your gravity measurements were off. If your gravity readings were mash(1.096), sparge(1.072), seems unlikely that 1L of extra liquid (even straight water) would have brought the pre-boil gravity down to 1.059. Have you calibrated your hydrometer? Did you check the temps when you took the various readings? Was your pre-boil sample pulled from the top of the kettle without stirring it up? I'd start with how the samples were pulled, what the temps were and whether the wort was sufficiently stirred up.

As for the OG (post boil I assume?) I would look at your grain crush, strike/mash temps...

 

[nicklawmusic]

The two runnings were take straight out of the mash tun through the bulk head.

The pre-boil gravity was from a sufficiently mixed wort.

I'll check my hydrometer again but pretty sure it's accurate at 20C.

I must confess, the crush on the Maris Otter wasn't great (I get it crushed, but this lot wasn't crushed as well as usual).

Mash and strike temps were spot on.

 

[Oginme]

Something is not quite correct in your measurements -- either volume or gravity.

From your mash you have collected 28 litres at 59 points gives you 1652 gravity points.

Post boil, you have 24.6 litres plus 3 litres of trub/kettle loss for 27.6 litres total at 64 points or 1766 gravity points. These numbers should be pretty close if you have good measurements.

Even if you drop the trub/kettle loss, you have 24.6 litres at 64 points for 1574 gravity points. Still way off target.

 

[nicklawmusic]

I'm not understanding about the gravity points?!

 

[Oginme]

It is a mass balance of the extracted materials using the specific gravity as points over 1.000 (water) and the volumes. Basically, the formula is (specific gravity - 1.000)*1000 * volume

When you collect your wort, you have extracted a certain amount of sugars, which we measure as the rise in specific gravity. This number multiplied by the volume gives a number which we call gravity points. During the boil, we concentrate the sugars in the wort by boiling away water. The amount of sugars pre-boil should be the same as the amount post-boil (assuming there are no additions of sugars during the boil).

This simple mass balance of sugars is a good way to ensure that your measurements of both gravity and volume are close.

In short:

Pre-boil volume x (pre-boil sg - 1)*1000 = Post boil volume x (post-boil sg -1) * 1000

 

[nicklawmusic]

Thanks. I understand how gravity works, it was more that I'm used to looking at it as 64 points (or 1.064). Wasn't quite following the 1652 or 1574 part.

 

[Oginme]

When you are looking at issues of efficiency, specific gravity readings mean nothing without knowing the volumes involved. You can come out 5 points low, but with a greater volume and reach the same mash efficiency.

When you are tracking down problems where your wort comes out low in gravity, you need to make sure that it is not because it is diluted from additional water which was drained out of the mash. Hence the material balance of following the amount of sugars in and out of the process.

 

[doug293cz]

Hi there,

I'm wondering anyone can help me. I brewed this last night (my own recipe):
http://beersmithrecipes.com/viewrecipe/796174/stout-to-the-lord-batch-no002

After the mash, I collected around 9L of wort of 1.096. My batch sparge collected around 17L of 1.072. I also ran 1 litre through a third time and collected that (though I didn't take a gravity reading of that).

What I don't understand is that my pre-boil gravity was only 1.059 when Beersmith said I should be hitting 1.072.

I added 400g of DME to this recipe to boost the final ABV and also added 400g lactose sugar as per the recipe and got an OG of 1.064.

Sorry, but your numbers just don't add up. There has to be a measurement mistake somewhere. I ran some projections for your recipe using the Beersmith grain database. Here are the results (sorry HBT won't let me post the actual spreadsheet with formulas)



Even if the last liter of sparge you collected had no sugar, your 27 liters of collected wort should have had an SG of 1.077, assuming 9 l @ 1.096, 17 l @ 1.072 & 1 l @ 1.000. This works out to 551.6 extracted gravity points out of a potential 606.6 (assuming lactose not in mash), for an apparent mash efficiency of 551.6/606.6 = 91%! The only way to get a pre-boil gravity of 1.059 out of your wort would be to add 27*77/59 - 27 = 8.25 liters of water to your collected wort. This would have given you a pre-boil volume of 35.28 liters.

Brew on

 

[beerme70]

Wow, that's too much for me to take in. This is MY science: Beersmith says post-boil gravity should be 'x' (roughly). I take my gravity reading, adjust accordingly for temp, and BLAMMO! If anything, if I don't hit my sg on the button, I actually get a little higher reading. If I am not mistaking, Beersmith calculates all it's numbers assuming 75% efficiency. I routinely hit in the ballpark of 80-85ish.

 

[Hex23]

Beersmith says post-boil gravity should be 'x' (roughly).

A small part of OP's problem may have to do with this issue:

https://www.homebrewtalk.com/showthread.php?t=528565

Assuming OP did not put the lactose in before measuring, the Beersmith predicted number is about 3.5 points too high

If I am not mistaking, Beersmith calculates all it's numbers assuming 75% efficiency.

Beersmith uses what you tell it to use. It either uses what you have set in the equipment profile, or overrides that if you set it in the recipe design sheet. It's a good idea to set this based on your experience with your equipment/setup so that you can hit your numbers. 75% is probably not a bad initial guess.

 

[Hex23]

Something is not quite correct in your measurements -- either volume or gravity.

I think this observation is the most important here.

... gives you 1652 gravity points. ... 1766 gravity points. These numbers should be pretty close if you have good measurements.

But I don't completely agree with this because OP added 800 grams of sugars between pre-boil and post boil, indicating that the numbers are even further off.

Overall, I agree with what most have said: there has to be some error in volume and/or gravity measurements. OP: Even if you discount the 800g of sugars you added between pre-boil and post-boil, for the gravity measurements to be right, it means you only boiled off ~2 liters, which seems unusually low.

Also, please clarify what you did during the mash. Did you really collect three separate volumes of liquid, measure each individually, then combine? Or are you taking gravity measurements of cumulative volumes? E.g. is the 1.072 measurement really for 26 = (9+17) liters?

 

[Gnomebrewer]

As Hex23 said, beersmith includes your lactose in the pre-boil gravity unless you've ticket to have it added after the boil. Also, it won't matter how much you've stirred, sugars tend to sit towards the bottom until you reach a rolling boil. Take your gravity reading after you reach a boil.

 

[nicklawmusic]

Take your gravity reading after you reach a boil.

Doesn't this defeat the purpose of a 'Pre-Boil' gravity reading?

 

[nicklawmusic]

I set my efficiency to 74%.

As for volumes, I must confess my kettle doesn't have markings on it, so I have to go by sight. I have measured the 30L mark, which I filled my HTL up and to then drained half of it into the mash tun at a time. The additional litre was just water from a kitchen kettle at 65C. I didn't leave that in the mash tun long.

As for crush, what does a good crush, what does a good crush look like? That's the only other thing I can think of, as the Maris Otter didn't look as crushed as it usually does.

Finally, if my volumes were off (which, despite not having markings, I don't think they wildly were), how does one either go about putting markings on a kettle or calculate the volume of water by height in the kettle?

 

[Gnomebrewer]

Take your gravity reading after you reach a boil.

Doesn't this defeat the purpose of a 'Pre-Boil' gravity reading?

No.

The gravity of the wort doesn't magically change when you reach boil. It changes through 60/90 minutes of water evaporating off.

 

[nicklawmusic]

So I'd be better taking a pre-boil reading at the start of the boil so all the sugars are mixed up? I guess that makes sense my first pre-boil reading was 1.050 but I took another one not long before the book just to check as I thought that was too low.

 

[Hex23]

As for crush, what does a good crush, what does a good crush look like? That's the only other thing I can think of, as the Maris Otter didn't look as crushed as it usually does.

There are probably literally hundreds of threads on this site with pictures addressing this issue.

Finally, if my volumes were off (which, despite not having markings, I don't think they wildly were), how does one either go about putting markings on a kettle or calculate the volume of water by height in the kettle?

Here are a few ways:

1) Install an aftermarket sight glass. This is really convenient since you don't have to stand over the kettle and you don't have to worry about the boiling surface making it difficult to measure. Here are some good examples: https://www.brewhardware.com/category_s/1819.htm

2) Make permanent markings on the inside of the pot. Here's a good thread, but I'm sure there are many way to do this:
https://www.homebrewtalk.com/showthread.php?t=463099

3) Use a measuring stick. You can just use a standard stick (e.g .with pre-defined cm markings), or just make your own out of stock metal and make your own markings.

a) For an unmarked stick, you could mark it by putting successive liters of water in and making a mark after each - or by using (b)

b) For a pre-marked meter stick: calculate a cm per liter for your pot. Calculate the cross sectional area of your pot: Measure diameter. Then, area = 3.14 * (diameter/2) * (diameter/2). If your measurements are in cm, then just divide 1000 by that number to get centimeters per liter.

E.g. for a kettle with 20 cm diameter, area = 3.14 * 10 * 10 = 314 cm^2.
(1000 cm^3 / liter) / 314 cm^2 = 3.18 cm / liter

 

[Oginme]

It seems as though your biggest issue is most probably with your estimate of volume. As Hex23 has indicated above, there are many ways to get a good measurement of the volume both pre-boil and post-boil.

To get an accurate measurement of your mash efficiency, you will need to take a sg reading of your wort before you add the sugars. Then again after you add any sugars pre-boil. Keep track of your volumes starting water, pre-boil, post-boil, fermentor, and loss to trub and you can use those numbers to improve your equipment profile. BeerSmith will better predict your outcome once you customize it for your process.

Hex23: Good catch on the lactose add. I wasn't paying attention to the exact recipe as much as the results pre- and post- boil.

 

[cyberbrew]

Finally, if my volumes were off (which, despite not having markings, I don't think they wildly were), how does one either go about putting markings on a kettle or calculate the volume of water by height in the kettle?

I literally use a measuring tape (all preboil so I'm not concerned with sanitization). And, because I'm super lazy, I use - http://www.calculatorsoup.com/calculators/construction/tank.php - set it to "Vertical Cylinder" drop in your diameter and height, then use your measuring tape for filled depth.

 

[Gnomebrewer]

So I'd be better taking a pre-boil reading at the start of the boil so all the sugars are mixed up? I guess that makes sense my first pre-boil reading was 1.050 but I took another one not long before the book just to check as I thought that was too low.

Yes. I only recently started doing this after having the same problem you are. It was suggested in another thread that gravity is better taken after the boil starts. It works much better than a true 'pre-boil' measurement.

As mentioned above, a measuring stick is useful for volume. Mine measures from the top of my kettle (converted keg) to the top of the liquid. Volumes are marked on the stick based on previously measured volumes of water poured into the kettle. In a keg, it works out to close to 1cm per litre.

 

[pricelessbrewing]

I use a metal ruler to measure volumes, and my biab calculator accounts for the height at each step.