Author Topic: Calculating Sparge volume in order to hit OG  (Read 3875 times)

Offline Pompeysie

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Calculating Sparge volume in order to hit OG
« on: May 04, 2015, 02:45:09 PM »
I always seem to have a problem hitting my OG. My beer tends to finish-up weaker than it should. Up until now I have followed Beersmith to the letter during brew days but I'm now thinking I need to go back to basics to try and help.

Here's where I need your help (my maths is not great!).

I am thinking there must be a calculation one can make which, taking into consideration loss to evaporation and loss to trub, allows me to work out how much sparge water i need to add to the wort after I have emptied the mash tun. I normally check the gravity at this point anyway.

Any help very much appreciated.

THanks

Simon

Offline twhitaker

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Re: Calculating Sparge volume in order to hit OG
« Reply #1 on: May 08, 2015, 03:22:53 PM »
 Managing loss is important when your losses are substantial in the beginning.  As Brewers  we are always trying to find ways to reduce losses with every batch made. I find if I know and have entered all loss values, including grain absorbtion and have them all entered into the recipe design, and  have a completely accurate  equipment profile, Beersmith gives me exactly what I need to know for water and I use that. Sometimes after going through all the volume and loss entries into the recipe you will find something off and once it's corrected for that recipe, the beer comes out exactly how it should next time.
Cooling loss, boil off rate, mash tun dead space, low mash conversion efficiency,transfer losses, bottling loss, all come into effect. If you make a 5 US gallon recipe  and your losses add up to 1 us gals, you are  making 4 gallons and should only bottle that much.  If you want to bottle 5 gallons  make 6. Until you get to the point where your losses are minimal. As long as you know the real value of your losses, and you have input those correctly in  to Beersmith,  CHEERS
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Offline Pompeysie

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Re: Calculating Sparge volume in order to hit OG
« Reply #2 on: May 08, 2015, 11:17:27 PM »
Thanks for the advice my friend. I'm wondering if my mash conversion efficiency is out. Do you use the grain yield potentials that come as default in Beersmith or add your own? Often these are not published by the shops where I buy my grain. Other than strike water temperature and thermal capacity of the mash tun, I can't imagine what else could effect this?

Simon

Offline philm63

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Re: Calculating Sparge volume in order to hit OG
« Reply #3 on: May 12, 2015, 11:14:46 AM »
As far as volumes for the sparge - you mean "...how much sparge water i need to add to the mash" not the wort, right? If you add your sparge water to the wort in your kettle instead of running it through the grain, you are not rinsing the sugars off the grain thus you will end up with a very weak wort. You could boil this down to hit your target gravity but you'd likely end up with a gallon or two, instead of 5, or whatever batch size you're shooting for, and your hop utilization would be way off. I kind of hope I am reading this wrong, but if not...

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Offline haerbob3

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Re: Calculating Sparge volume in order to hit OG
« Reply #4 on: June 05, 2015, 03:23:16 PM »
Are you checking your pre-boil gravities?  I use a temp correcting refracometer for this.  Something I found very helpful is to have my HLT & MLT on a wedge so that the dead-space is nearly nonexistent.  Boil-off is harder to zero in as it changes with the humidity level.  I live in Michigan and there is a fair difference in winter vs summer.

Offline durrettd

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Re: Calculating Sparge volume in order to hit OG
« Reply #5 on: June 06, 2015, 11:27:43 AM »
+1 to h3 for his wedge and refractometer comments. Both make my life easier.

One thing that does NOT make my life easier is that my "Automatic Temperature Correcting (ATC)" refractometer is capable of only a limited range of temperature correction; I have to grab a small sample of hot wort, let a few drops fall into a heavy glass container, then let it cool for a few seconds before dripping the sample onto the refractometer glass. If I drop the hot wort onto the refrtactometer, I get wildly varying and continuously changing readings.

Required addendum to any mention of refractometers: alcohol affects the refractive index of beer differently than sugar. Once beer begins to ferment, the refractometer reading must be corrected for the presence of alcohol. BeerSmith has a tool to make the correction.

 

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