First All-Grain Tonight; Question on my Water Volume/Temp Calculations

Hello all,

Got all my gear ready to go for my first AG batch tonight; my yeast starter is sitting next to me and appears almost as excited as I am. Having a little confusion on water volume/temp and looking for a little direction.

Here are the details: AHS Alpha King Clone; 5 Gallon; 12.3 lbs grain; Mash Temp 150 degrees; 90 minute boil. Will boil outside tonight, probably at around 45 degrees Fahrenheit (chose a bad night for a 90 minute boil!).

---AHS instructions say:---
- Strike 170 to get to 150 degree mash
- mash 3.84 gallons for 1 hour
- sparge 5 gallons at 175 degrees until you have 6.25 gallons in the pot (they emphasize this: "Don't run off more than 6.25 gallon of wort!")
- If not getting 5 gallons in fermentor at the end of the process, add extra cool water to top off the fermentor.

---Brew365 calculator says:---
- Strike 162 to get to 150 degree mash
- mash 4.09 gallons for 1 hour
- sparge 5.25 gallons at ? degrees (and presumably drain it all, which, all things being equal, would give me around 6.75 gallons of wort to start.


Questions:


Thanks very much for your help!

Strike water temp is going to be dependent on the water:grain ratio as well as your specific equipment, temp of the grain, temp of the mash tun before adding water and grain.....

There is no one answer to the question.

The instructions from AHS tell you to stop to avoid the risk of over-sparging your grain, which can lead to off flavors.

If you need to add water to get to the final volume you want, I would do it as soon as you turn off the boil. If you know how much is in the kettle when the flame turns off, you can bring it up to where you want it while the wort is still hot (thus sanitizing the water you are adding). Then you can chill it all.

elganso said:

Hello all,

Got all my gear ready to go for my first AG batch tonight; my yeast starter is sitting next to me and appears almost as excited as I am. Having a little confusion on water volume/temp and looking for a little direction.

Here are the details: AHS Alpha King Clone; 5 Gallon; 12.3 lbs grain; Mash Temp 150 degrees; 90 minute boil. Will boil outside tonight, probably at around 45 degrees Fahrenheit (chose a bad night for a 90 minute boil!).

---AHS instructions say:---
- Strike 170 to get to 150 degree mash
- mash 3.84 gallons for 1 hour
- sparge 5 gallons at 175 degrees until you have 6.25 gallons in the pot (they emphasize this: "Don't run off more than 6.25 gallon of wort!")
- If not getting 5 gallons in fermentor at the end of the process, add extra cool water to top off the fermentor.

---Brew365 calculator says:---
- Strike 162 to get to 150 degree mash
- mash 4.09 gallons for 1 hour
- sparge 5.25 gallons at ? degrees (and presumably drain it all, which, all things being equal, would give me around 6.75 gallons of wort to start.


Questions:

1. Is there a reason to stop sparging at 6.25 gallons vs. getting more like 7 gallons to begin with? I'm concerned about evaporation rate with a long boil outside on a cold night. How does this choice affect efficiency (if at all)?

2. If evaporation is a problem, when is the best time to add water to the wort? I assumed sometime during the boil itself to top things off, but not sure if just adding sterile water to the fermentor would do the same thing.

3. As for strike and sparge temperature -- do I go with 170/175 or 162/? ? I'm not quite sure why these would differ so much between the two instructions?​

Thanks very much for your help!

Click to expand...

1) below a certain OG you will begin to extract undesired tannins. 7 gallon my be o.k., but I'd stick with AHS' instructions and limit to 6.25 pre-boil and top off post boil.

2) Top off post boil

3) Bobby_M provided an excellent post just today. Have a look.

https://www.homebrewtalk.com/f36/how-mash-tun-infusion-temperatures-work-173973/

good luck with your brew. I'm sure all will turn out well.

You can go here and get a better strike temperature calculation based on the actual temperature of your grain:

http://www.rackers.org/calcs.shtml

I heat the strike water 8-10 degrees higher and put it in my MLT (5 gallon round). 5-10 mins later when the temperature drops to the calculated strike temperature, I add the grains. I've always either nailed the mash temperature or been within 1-2 degrees.

3.84 gallons to 12.3 lbs gives a 1.25 quart/pound ratio which is what I like to use.

As far as the sparge, I'm not sure as I fly sparge. I let mine run until I get the preboil volume I want. My 32 quart turkey fryer pot boils off about a gallon/hour. I like to get 5.5 gallons in the fermentor so for a 1 hour boil I sparge to get 6.5 gallons, and for a 90 minute boil, I sparge to get 7 gallons. I have never added water to the wort other than running it through the grains first. Also, I have never had any astringency problems from over sparging.

I think the difference you see in the instructions is AHS ones includes the extra degrees to preheat your MLT and the Brew365 ones doesn't.

Use the calculator and I think you'll get closer to your desired mash temperature.

Looks like I was at about 72ish % efficiency, sparged until I got 7 gallons and pretty much hit the 5.25 gallons on the head in the fermentor. Lots of evaporation with cold and wind tonight...

We'll see how she ferments. Thanks everyone for your comments... they were extremely helpful.

Cheers!