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Things I've Learned Brewing with The Grainfather, Part 2

In the last post, I shared an overview of The Grainfather, recommended equipment to use with it, and an overview of the brewing process.  In this installment, I'm going to talk specifically about mashing and sparging. Having brewed over a dozen batches with it, I'm finally becoming very comfortable with the device, the mash process, and how to get what I want out of it. I don't consider myself a "master" of it yet, though.

For those who have never done all-grain brewing, I want to provide a quick overview of the mash process itself.

Mashing - With or Without The Grainfather

The goal of mashing is to turn the starches in the grain into sugars. More specifically, you want to turn the starches into a mix of fermentable and unfermentable sugars that provide the flavor profile associated with the beer you are brewing. A sweeter beer might warrant more unfermentable sugars. A more dry beer will demand few unfermentable sugars.

To a great extent, controlling the amount of unfermentable sugars is a function of mash temperature. The lower the mash temperature, the more fermentable sugar you'll have in the finished wort and the more dry the beer will be. It will generally also be thinner in body and higher in alcohol. The higher the mash temperature, the more sweet and full bodied the finished beer will be. That's simplifying the mash process a lot, but it's a good basic rule of thumb.

Extraction of sugar from the grain is primarily a function of the water-to-grain ratio, the enzyme levels of the grains, and time. The longer you mash, the more time the enzymes have to turn the starches into sugars. The higher the water-to-grain ratio, the weaker the enzyme levels will be and the longer it will take to convert all the starches into sugars. Experts like John Palmer suggest that an ideal water-to-grain ratio in a mash is 1.5 quarts per pound of grain. The Grainfather needs a little thinner (more water) mash than that, and tends to come out closer to 1.6 or 1.7 quarts per pound. I often compensate for this thinner mash by adding 10-30 minutes of mash time just to ensure full conversion, but that's not strictly necessary.

It's important to note, but beyond the scope of this post, that there are different enzymes at work during the mash process. Each enzyme has a temperature range at which it works best, and one above which it is destroyed. For this reason, there are recipes that involve multiple temperature ranges or "steps" designed to allow specific enzymes to function before moving to the next temperature or step. The Grainfather can accomodate these "step mashes" by simply changing the temperature setting on the controller.

Just before we end the mash, we increase the temperature inside the kettle to 168F or "mash out" temperature for about 10 minutes. This accomplishes two things. First, it stops most enzyme activity so that our flavor profile should be locked in. Second, it heats the grain bed so that the sparge water should flow more easily through it in the next step.

At the end of the mash, the grain is removed from the wort and allowed to drain into the kettle. There will generally be additional sugar "stuck" to the grain at the end of the draining process. This is why we sparge or "rinse" the grain at the end of the mash.


Sparging is the process of extracting the last of the sugars from the grain by running hot water through the grain bed and allowing it to drain into the kettle. You can definitely skip the sparging process if you want to, and you'll still produce a good beer. However, sparging is a great way to get the most out of the grain you spent your hard-earned money on. If you don't sparge, you'll need to top up the kettle with enough water to make the pre-boil volume.

It's important to have your sparge water at the appropriate temperature (168F) and ready to go when you lift the grain basket out of The Grainfather. Once the initial water in the grain basket has mostly stopped draining, you'll want to start putting the sparge water in the top of the grain basket to begin rinsing the sugars off grain and into the kettle.

In my experience (meaning this isn't the only way to do it), I've found that "batch sparging" or putting all the sparge water into the basket at the start of the sparge, works just fine. I've achieved very high efficiency doing this. It's probably faster than trying to fly sparge or gradually sparge the grain bed, but you can do what works for you.

Here's an important note. If you are planning to measure your pre-boil volume at the end of the sparge, take a moment to stir the wort first. If you don't, you may find that your pre-boil gravity reading is very, very low. This is because the thinner sparge water will tend to sit on the top of the kettle while the thicker existing wort lives in the bottom.  Stirring at the end of the sparge will homogenize the gravity and give you a more accurate reading.

Recommendation, Tips, and Tricks for Mashing and Sparging

Having done this quite a few times, I've had the opportunity to make a lot of mistakes. I'd like to save you the trouble of making some of them.

Tips for Loading the Grain Basket

  • To get the gasket to stay on the bottom of the grain basket when you insert it, it is helpful to make sure the gasket is wet first. It will slide in place a lot easier. Ditto the top of the basket. I growled and grumbled a lot about what a pain this process is before I figured this trick out.
  • When loading the grain, I use a scoop to sprinkle it on the mash water. Every few scoops, I stir the grain to make sure it's all getting wet. If you dump the grain all in at once, that's not going to be easy to do. My mash efficiency (per BeerSmith) tends to be around 88.5%.
  • When putting the top on the grain basket, don't compress the grain bed but do try to get the top of the basket as far below the recirculation pipe as you can comfortably do. This will keep the mash water from overflowing.
  • If you're using wheat and/or oats in the mash, make sure you include rice hulls. This will help the wort flow through the grain bed. Also make very sure to do a mash-out step to heat the grain bed before sparging.
General Mashing Tips
  • Don't lift the grain basket out of the kettle until you're ready to sparge. In one case, I thought I had a stuck mash and a lot of sediment (and grain bits) in the kettle. I lifted out the grain basket and set it aside while I scraped sediment off the heating element. This allowed bacteria in the grain to work on the sugars, souring the mash. The finished beer, instead of being slightly sweet, was moderately sour from this unintentional "mash souring".
  • Calculate the mash water correctly. It's not necessarily obvious in the manual, but the correct mash water formula for a typical 5-gallon batch of beer is:

    (Total Grain Bill in Pounds x 0.34) + 0.9 = gallons of mash water

    For a 10 pound grain bill, that works out to:

    (10 x 0.34) + 0.9 = 4.3 gallons of mash water
  • Calculate the mash thickness to determine if you should extend mash time. Once you have the mash water volume calculated, convert that to quarts by multiplying by four. Divide that by the number of pounds of grain to get your mash water to grain ratio. If this is much higher than 1.5, you may want to extend the mash time by 10 minutes or more. If you extend it too far, you may end up with a thinner beer after fermentation because the wort is "too fermentable". Practice will help you dial this in. (Translation - I'm still working on it.)
  • iMake's Graincoat accessory will help keep mash temperatures more steady. It also speeds up the heating of the wort quite a bit.
  • Check the manual for each mash temperature you plan to use. There is a table in the manual that suggests changing the heating mode switch from Mash to Normal depending on the mash temperature you're trying to maintain. Ignoring this can cause the mash temperature to vary widely in some conditions.
  • Consider pH 5.2 Stabilizer. This product is available from many brewing shops. I've found that I get a little better efficiency and beer when I use it versus when I don't. Your experience may vary, but it's not a very expensive substance to add to your mash. Don't add it until the grain is in the kettle.

General Sparging Tips

  • Calculate sparge water correctly. The manual's "big print" formula for calculating mash water assumes a 6-gallon batch size, versus the 5-gallon batch size most home brewers make. The following formula has worked well for me:

    ((Batch Size in Gallons + 1.4) - Mash Water in Gallons) + (Grain Bill in Pounds * 0.1)

    So for a 5-gallon batch with 10 pounds of grain, we'd come up with 4.3 gallons of mash water using the formula shown in the mash section above. That would make our sparge water calculation:

    ((5 + 1.4) - 4.3) + (10 * 0.1) = 3.1 gallons of sparge water

    Why is this important? If you sparge with too much water, you're going to end up with a lot more in the kettle before you boil than you need. You'll end up having to boil the wort for a while before you get to the first hops addition, which will increase brewing time and might cause Maillard reactions in the kettle that darken the beer more than you intended.
  • Time your sparge water heating. One method recommended in the manual is to boil your sparge water in The Grainfather, then pump it into your fermenter (or another vessel that can handle the temperature). The sparge water will gradually cool over time to sparge temperature and can then be poured onto the grain bed once the basket is lifted from the kettle.

    In my case, I use an induction cooktop and stainless kettle to heat my sparge water while the mash is underway. It takes approximately 30 minutes for this combo to heat water to 168F, so I start heating about 30 minutes before mash out so that my sparge water is ready to go when the grain basket comes out of the kettle. If you don't do this, there is a chance that bacteria in the grain could sour the mash a bit before your spare. At the very least, your total brew time will be increased significantly.
  • If you heat sparge water in another vessel, consider dead space. In my case, I use a Mega Pot 1.2 on an induction plate to heat the water. I have this sitting on a hand-made table that's high enough to place the Mega Pot's valve above the height of The Grainfather's grain basket. This allows me to use gravity to transfer sparge water onto the grain basket. I don't have to lift the sparge water kettle and risk burning myself or spilling hot water. The down-side is that the kettle, as I have things setup, leaves about a gallon behind. So I have to add a gallon to my sparge water calculation to account for the dead space below the valve. That way I don't have to lift the huge hot kettle and pour out the last of the water. I can wait until it cools down and dump the leftover water in the sink and use it for cleaning.
  • Calculate pre-boil volume you need. The US Grainfather boils off water at the rate of approximately 0.4 gallons per hour. For a 90-minute boil, that's 0.6 gallons. If you want 5 gallons in the kettle after a 60-minute boil, you need 5.4 gallons in the kettle before the boil begins. If you're doing a 90-minute boil and want 5 gallons, you'll need 5.6 gallons of wort in the kettle at the start of the boil. If your sparge water calculation was off, you may need to boil longer than planned (if you had too much) or add water to the kettle before boiling (if you didn't have enough wort).

Following all these tips has helped me to achieve correct pre-boil volumes and gravities, which in turn ensure that my post-boil volumes and gravities line up as well.


  1. I want to double down on what you said about the rice hulls in a mash with wheat and oats as well as the need for for more strike water. I recently mashed with wheat which soaked up so much water that the pump kept losing it's prime. Rice hulls and more water would have solved all that and restored my loss in extraction.

    Another tip would be for the post brew cleaning process. A good way to prepare for cleaning and to save water would be to put some PBW in a bucket and fill it with the hot water that is coming out of your counterflow chiller. You'll chill the beer and end up with a bucket of hot cleaning water for you kettle/tun.

  2. Hello!

    I was searching for tips about the Grainfather, I started brewing with it for about 1 year and a half ago, and I was wondering about the efficiency...
    How do you reach a 88.5% ?!
    I think that I do everything correctly, but the maximum that I had, before the boil, was 82%, for the majority of my recipes, I'm around 72% and after the boil it can drop to 68%...
    If you have time to give me some specific advice, tell me, and I'll contact you by mail!


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