Batch Sparge vs. Fly Sparge

Batch Sparge vs. Fly Sparge

In this post, we’ll break down the differences between batch sparge vs. fly sparge for homebrewing.

For a long time, we used kits to brew our beer. Most beer kits are extract-based, so no sparge is required. However, as we’ve moved into all-grain brewing, learning the age-old tradition of sparging has become necessary.

For many homebrewers like us, who are new to all-grain brewing, sparging is scary and can create confusion, especially since it requires learning a new language, more equipment, and some added time to the brewing process.

After our first attempt at all-grain brewing, we realized that sparging isn’t so bad, even if it comes with its own language. Actually, sparging is a critical step in all-grain brewing and is the key to a good original gravity and creating a more consistent beer product.

What is Sparging?

Before we get into the two sparging techniques used by homebrewers and in larger brewing operations, it might be helpful to explain what sparging is and why it is so important to create a great beer. 

Many homebrew sites are pretty technical with their explanations, so we’ll try to be straightforward. However, we found that the American Homebrewers Association was helpful as a reference for how to sparge if you need some extra information.

Sparging is the process of rinsing additional sugars from the grains in the mash. This is the final step in the lautering process. Sparging uses warm water to rinse the grains to ensure maximum sugar extraction from the grain and lautered to the boil kettle.

For reference, lautering is the process of separating the sweet wort from the grains. The basic process for lautering is the same for both sparge methods, though the techniques are pretty different. 

Typically, the lauter starts by increasing the temperature of the mash. This is called the mashout. The ideal temperature for the mashout is no more than 170 degrees Fahrenheit. If the temperature of any part of the lauter or sparging goes above 170 degrees, you risk introducing tannins from the grain to your wort. This can cause a bitter taste in your beer.

The lauter then proceeds by draining a bit of wort out of the mash tun and returning it over the top of the mash and back through the grains. This process of recirculating the wort is called “vorlauf” in German. Vorlaufing is used to create a filter bed from the grains, which clarifies the lauter.

Once the grain bed has been established, and some of the wort has been recirculated through the grains, the wort is drained from the mash tun into a lauter tun or the boil kettle, leaving the grains behind. 

The grains are then rinsed using clean water heated to no more than 170 degrees Fahrenheit. This heated water (sparge water) and the process of introducing sparge water to the mash is sparging.

There are two ways to sparge: fly sparging and batch sparging. Homebrewers use both sparging techniques, and when done correctly, both work very well at producing a consistent wort that becomes a great beer.

Determining which sparge method you want to use in your homebrewing process depends on how much time you have on your brew days and how much money you want to spend on equipment. To help you work through this decision-making, we’ll now break down the differences between fly sparging and batch sparging.

Batch Sparging

Batch sparge vs. fly sparge
Batch sparging uses less equipment

Batch sparging is the quickest, and simplest sparge method. Batch sparge is also the method that most homebrewers use in their all-grain processes. We like batch sparging because it uses less equipment, and you can easily lauter and sparge with only a mash tun with a false bottom or cooler, a boil kettle, and an extra pot for heating the water.

While a staple in the modern homebrewing process, batch sparging is probably a descendant of the Partigyle style of mashing popular among English brewers in the 19th century. The Partigyle brewing process completely drains the wort from the mash and uses the original wort for one beer and the sparge rinse for another beer. In the batch sparge method, we drain the wort from the mash and then add the sparge rinse to the same boil kettle to make one beer.

If you are using a cooler for your mash tun, you may want to do a bit of a DIY project and add a spigot and tubing to the cooler for easier lautering of your wort. Also, if you aren’t ready to invest in more pots and need to use your boil kettle for heating your sparge water, your bucket fermenter can double as your lauter tun in a pinch.

As a matter of safety, do keep in mind that you will need to pour hot water into a cooler or mash tun with the batch sparge process. Take your time and go slowly, so you don’t risk getting burned.

The Basic Steps For Batch Sparging:

  1. Start your mash in either your mash tun or cooler. Allow the grains to steep for the necessary amount of time for the beer style you are brewing. This is usually around 60 minutes for complete starch to sugar conversion.
  2. If you’re using an actual mash tun, you’ll want to keep an eye on the temperature of the mash to ensure that it doesn’t drop below around 145 degrees Fahrenheit. If it gets too low, turn on your burner and allow the temperature to rise back to the 160-degree range.
  3. At the end of your 60 minutes, either heat the mash to 170 degrees by turning the burner back on under your mash tun or add enough additional water to your cooler to increase the temperature. This is your mashout step.
  4. Following the mashout, drain a portion of the wort from the mash tun/cooler into a pitcher or pot and slowly pour it back on top of the mash to create a grain bed. The grain bed will act as a filter that will separate the wort from the grains and help to keep husks and grist from ending up in your boil kettle.
  5. When the grain bed has settled, lauter the wort completely from the mash tun to the boil kettle. Shut the spigot of the mash tun. Measure the specific gravity of the wort so that you can gauge the amount of water needed in the sparge.
  6. Add warmed sparge water to the cooler and stir.
  7. Let the sparge water sit for approximately 10 minutes. 
  8. Drain the sparge water directly into the boil kettle with the mash wort.
  9. Check your specific gravity. If the original gravity (OG) is correct after one sparge, you are ready to boil. If it is not, repeat steps five through eight.

The number of sparge batches you complete depends on your preference or how efficient the mash process was at extracting sugars.

One thing to remember is that batch sparging lacks mash efficiency compared to fly sparging when it comes to a complete rinse of sugars from the grain bed. However, for homebrewers making less than 15 gallons at a time, this loss of efficiency won’t make a huge difference in your beer. However, you can remedy this by adding an extra pound of grain to your mash.

Fly Sparging

The process of fly sparging is the most typical sparge method that you will find in a commercial brewhouse. Homebrewers who have increased their brewing capacity or want to have more consistency often move from batch sparging to the fly sparge technique.

If you’re brewing larger quantities of beer, fly sparging means better efficiency in separating sugars from the grains, which means you use less malt. Less malt means lower costs. For many homebrewers, this savings in malt costs is worth the extra time and equipment necessary for fly sparging.

Commercial brewing systems rely solely on fly sparging since it is the most efficient, and brew time isn’t a factor in large production brewhouses.

Fly sparging is also referred to as “continuous sparging.” The basic process of fly sparging requires that sparge water is slowly sprayed over the top of the grain bed, and at the same time, lautered at an equally slow flow rate into the boil kettle. This is where the name “continuous sparging” stems. 

Continuous sparging also eliminates the potential for channeling through the grain bed to occur. Channeling is when the sparge water is added too quickly to the mash and only passes through small areas of the grain. If channeling occurs during the sparge, not all the grain is rinsed, and you lose efficiency. This is why it is so essential to manage the flow rate of the sparge water and lauter.

The fly sparge process requires a lot more equipment than is needed for batch sparging. If you are interested in this sparge method, you will need to invest in a mash-lauter tun with a false bottom, a pump to transfer sparge water, a sparge arm, a pot for heating your sparge water, and finally, a boil kettle.

We have seen homebrewers make mash-lauter tuns with sparge arms using an old keg. So if you’re ready to move to fly sparging but don’t want to spend a bunch of extra money on new equipment, you can DIY a lauter tun with sparge arm for not much money.

When fly sparging, you will want to start your process much as you did for the batch sparge, starting the mash in the mash-lauter tun. Then, after steeping for the appropriate amount of time, start your mashout. 

Then, lauter a small amount of wort from the mash tun, return it to the top of the mash and stir gently. The vorlaufing will recirculate the wort through the grains, and as the grains settle, create the grain bed. It is crucial that your grain bed in fly sparging is between 4 and 8 inches deep for the best filtering and to reduce the potential for a stuck sparge.

As you begin your sparge, you will partially open the spigot to the sparge arm and allow a small flow of water to pour over the top of the mash. At the same time, you will partially open the spigot on the mash-lauter tun and allow the wort to lauter into the boil kettle. 

As best as possible, match the flow rate of the sparge arm to the flow rate out of the lauter for the best results. If the flow rate of the lauter is too fast, you can create a vacuum within the tun, which causes stuck sparge.

Stuck sparge is a condition where the lauter stops during the sparge. This is not generally a concern with batch sparging, but it can be a big annoyance with fly sparging. Besides too high lauter flow rate, stuck sparge can be caused by high gluten grains like wheat, a thin grain bed that allows husks to pass through and stick in the spigot or tubing, or mash that is ground too fine, causing grist to pass into the lauter.

During the fly sparge process, you will want to monitor the specific gravity of the wort in the boil kettle. This will ensure that the wort has the correct pre-boil OG. The sparge is complete when the wort specific gravity is around 1.010.

Brew In A Bag

It is of value to note that all-grain brewing can be accomplished without a sparge. Many homebrewers who want to experience all-grain brewing but don’t have the space or funds for lots of equipment may want to try the brew in a bag (BIAB) process. 

BIAB is kind of like making tea. You fill your boil kettle with water to the pre-boil volume and heat to the appropriate mash temperature. To the hot water, you insert the mesh bag and fill it with your milled grains. After the grains steep for an hour, you simply remove the bag. If you’re brewing 5-gallons by BIAB, you’ll want to make a pulley system to lift the bag from the boil kettle, as it will be quite heavy. The water drains from the grains, and you’re ready to boil. No sparge necessary.

The BIAB process is easy and works well for small quantities. However, keep in mind that of the three options, this one is the least efficient in rinsing sugars from the grain. But it may be a good first step for the all-grain novice to experiment with a new process before investing in the equipment necessary for batch or fly sparging.