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Improving Mash Efficiency: Tips & Techniques

Having a poor mash efficiency can be one of the most frustrating issues as a brewer. Fortunately we have a few tips and techniques to consider that may help you with this issue.


This is the first control point in the brewing process that can help improve your mashing efficiency.

The varieties of grains you select within your recipe can have an impact on the movement of water throughout your grain bed. This restricted water flow can therefore reduce the ability for fermentable sugars to be removed/washed from your grain and ultimately reduce your mashing efficiency.

In some cases the water movement within your grain bed can also completely stop, commonly known as a stuck sparge. This would be the worse case scenario. Common grain varieties know for creating this issue are husk-less varieties such as wheat and rye.

It’s important to understand that the husk of the grain plays an important role in aiding the filtration of solid matter within your grain bed. This filtration activity helps create a loose free-flowing grainbed. However, due to the husk-less nature of the previously mentioned grains, this important filtration action is reduced and results in a sticky mash consistency.

Recipe Design – Best Practises

In order to avoid or reduce the restriction of water flow throughout the grain bed, first review your recipe…

Does your grain bill contain over 20% of a husk-less variety such as wheat or rye? If this is the case, there are 2 main actions you can take:

  1. First you can add an additional 100-200g of rice hulls to your grain bill. This addition will help with the filtration of solids and water flow movement within the grain bed.
  2. Second you can reduce the amount of husk-less varieties within your recipe to help avoid potential water flow issues.

If the worse case scenario of a stuck mash is created, your best action is to stop any recirculation and give you mash bed a solid stir. This manual stirring will release the grain bed and allow water to move back through the grain bed.


The quality of your grain crush can have a significant impact on the efficiency of your mash.

Too fine and you restrict the ability for water to move through your grain bed efficiently. Therefore reducing the amount of fermentable sugars that make it into your boil kettle.

Too coarse and you reduce the amount of exposed starch to potentially convert into fermentable sugars. Plus water movement through your grain bed is increased and reduces the efficiency of your sprarging process.

Finding the happy medium of your crush size can be a difficult process considering the perfect crush size may vary from system to system. However, for a starting point there are a few benchmark standards you can aim for that will help improve your mash efficiency.

Milling – Best Practises

The typical characteristics of a ‘good crush’ should be as follows:

  1. You can visibly see the grain husk in tact.
  2. Minimal (<10%) visual of ‘flour’ contained within your grain crush
  3. Grain cracked into 3-4 separate parts.
  4. No grain should be completely left in tact.

Too Coarse


Too Fine


When ‘mashing in’ one major factor that can cause a significant hit of your efficiency is the formation of ‘dough balls’.

Dough Balls are clumps of grain that are formed at the point of when you add your grain to your strike water. The major issue with dough balls is that they create dry sections of grain which never come in contact with the water. This results in unconverted grain which therefore reduces the overall efficiency of your mash.

Mashing In – Best Practises

In order to avoid this issue there are a couple of actions you can take.

  1. Add the grain slowly to your strike water and never dump the total grain bill in at one time.
  2. As you’re adding your grain slowly to the strike water, have an extra person on hand to continually stir as you are adding the grain. This will help break up any dough balls that form.
  3. If you don’t have a second person on hand, add your grain in small batches and give your mash a good stir in between additions.
  4. Once you have added your total grain bill to the mash tun, give it a good stir to break up the remaining dough balls that may have been formed.
  5. After mashing in Is complete, wait at least 5 minutes before you begin any recirculation.


By including recirculation into your brew system, you will see a major improvement on your mashing efficiency.

The action of continual water movement throughout your grain bed will aid in the physical removal of fermentable sugars within the grain. The additional bonus of recirculation is that it will help with filtration and clarification of your wort.

Recirculation – Best Practises

The first best practice of recirculation is to actually include it into your brewing system/process. A lot of brewing systems are built with out the use of recirculation and if your mashing efficiency is poor, it should be a major consideration.

If you already have a recirculation setup installed into your system be sure to make sure your recirculation isn’t creating a ‘channeling’ effect that will reduce the overall contact of water with your grain bed.

You can help avoid channeling by:

  1. Controlling your recirculation speed
  2. Ensuring you have at least 2-3cm of wort covering the total surface of your grain bed throughout your mashing process
It’s also important to ensure your are not recirculating too fast. This action may cause your grain bed to ’suck in’ and compress, therefore restricting water movement throughout the grain bed.


The act of sparging (rinsing your grain) is a process that is essential if you are looking to improve your mashing efficiency. The sparging process will aid in the physical removal of fermentable sugars from your grains.

If you do not include this process into your brew day, you will essentially be leaving a significant amount of fermentable sugars trapped within your grain bed.

Even using a small amount of additional sparge water rinsed through your grain can make a significant improvement on your mashing efficiency.

Sparging – Best Practises

Firstly, if you have not already included a sparging process into your brew day, this is essential for improved mashing efficiency.

As stated earlier, even a small amount of sparge water (5-10L for a 23L batch) will see significant improvements.

To get the most improvement from this process it’s important that when you sparge the surface of your grain bed is slightly exposed as you sparge. If you are using a 3V system, it is good practise to first begin your transfer of wort from the mash tun to the boil kettle until the surface of your grain bed becomes slightly exposed. Once you begin the sparging process, aim to match the speed of your transfer with the speed of your sparging in order to maintain the level of water on top of your grain bed. Maintaining this level will help create even movement throughout the grain bed which therefore helps extract the maximum amount of fermentable sugars from your grain.

Maintaining this level will also reduce the risk of running your grain bed dry. Leaving your grain bed too dry tends to create compressed sections throughout your grain and bed and therefore restricts the movement of your sparge water.

As you sparge, pay close attention to the disturbance of your grain bed. You ideally want to create minimal disturbance in order to create a nice clear flow throughout the grain bed.

Lastly, ensure you sparge with enough water to enable you to extract the maximum amount of sugars from your grain therefore maximising your mashing efficiency. A good rule of thumb to work from is to sparge until the exiting wort from the mash tun is around 1.013 in gravity.

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