How to Fix a Stuck Sparge or Mash on a BrewZilla

If you're using a single vessel brewing system like the BrewZilla and like incorporating ingredients like wheat and oats into your grain bill, there's a good chance you're going to experience a stuck mash or a stuck sparge. In this article, we'll take a look at exactly what these are, and what you can do to save your brew day if it happens to you.

Introduction

The BrewZilla is a popular all-in-one brewing system among homebrewers. However, stuck sparges are a common issue that can really slow things down in the middle of a brew day. Maintaining a smooth brewing process is crucial, and knowing how to fix a stuck sparge can save you plenty of time and frustration. 

What Is A Stuck Mash?

When undertaking an all-grain brew on a BrewZilla (or similar all-in-one brewing system), you should use the built-in pump and recirculation arm to recirculate the wort back over the top of the grain bed during the mashing process. This aids in increasing efficiency, and also helps to clarify the wort as the grain bed acts like a filter. 

The pump inlet for the BrewZilla is at the base of the unit

Since the wort is drawn from the pump inlet at the base of the BrewZilla unit, the wort must flow back through the grain bed during recirculation at a similar rate to what it is being pumped back up via the recirculation arm. If the flow speed through the grain bed becomes too slow, the dead space between the false bottom and pump inlet can become dry, which can damage the heating elements on your BrewZilla. 

A stuck mash occurs when the wort stops flowing back through the grain bed during the mash, and becomes "stuck".

What Is A Stuck Sparge?

Sparging happens after the mash when the malt pipe is lifted from the BrewZilla and sat on the halo ring suspended above the wort within the boiler. Sparge water is then used to rinse any residual sugars from within the grain bed.

The malt pipe needs to be lifted from the BrewZilla boiler for sparging

Similar to mashing, sparging requires water to be able to flow through the grain bed and into the BrewZilla boiler to make up the required pre-boil volume for the batch of beer being brewed.

A stuck sparge is when the water stops flowing back through the grain bed during the sparging process, and becomes "stuck".

Methods to Fix a Stuck Mash or Stuck Sparge

There are several methods to resolve a stuck mash or sparge if you encounter one during your BrewZilla Brew Day. Some are preventative, and some can be implemented on the spot if you get "stuck."

1. Don't Use the Fine Mesh Bottom Screen

• Helps with a stuck mash or stuck sparge. 

• If you're BrewZilla came with the fine mesh bottom screen, we'd recommend you don't use it and just stick with the standard bottom screen. 

• In our experience the finer mesh screen is not required and the tighter mesh pattern can hinder the flow of wort back through it and gets clogged with grain particles very easily.

Don't use the fine mesh bottom screen

• Note: If you're in the middle of your mash or sparge then this screen can't be removed. Your only option at this point is to give the grain bed a good stir, making sure you get your mash paddle right down to the bottom of the malt pipe to help loosen the grain stuck around the fine mesh screen.

2. Perform a Mash Out Step

• A mash out step can help prevent a stuck sparge and involves raising the temperature of the grain bed from mashing temperature (around 65°C - 68°C) up to 75°C and holding it at this temperature for 10 minutes.

Get the temperature of your grain bed up to 75°C for 10 minutes to perform a mash out

• The warmer temperature will make the wort less viscous and increases it's ability to flow back through the grain bed.

3. Use Rice Hulls

• Rice hulls can be incorporated into the grist to improve the ability of water to flow back through the grain bed

• Rice hulls do not impart any sugar, colours, or flavours into the finished beer, so are safe to use with any recipe.

Rice hulls can help prevent or fix a stuck mash/sparge

• Always keep some rice hulls on hand as they can be added to the grain bed at any point to try and fix a stuck mash or stuck sparge.

• We always incorporate rice hulls into the grist if we're using oats and/or wheat, as these often lead to a thick, sticky mash that is prone to becoming stuck.

• Stir them into the grain bed after adding them.

• Add more rice hulls if the flow of wort is still slow or stuck after initially adding some.

4. Use Hot Sparge Water

• Make sure your sparge water is as close to your desired sparge temperature (75°C) as possible.

We use a Digiboil to heat up our mash water to our target temperature 76°C

• Using sparge water at the same temperature as the grain bed will help it maintain temperature, and lower its viscosity.

• A separate sparge water heater like a Digiboil can help with this, as it has a digital thermostat giving accurate temperature control for the sparge water.

5. Stir the Grain Bed

• Stirring the grain bed can help aid water flow if it gets stuck during mashing or sparging.

• Stir with a mash paddle and be sure to get the paddle right to the bottom of the malt pipe to loosen the grains around the bottom screen.

Make stirring easier by using a specialised drill attachment

• During the mash, you can stir using a drill attachment to make the stirring process quicker and easier.

• Repeat the process of stirring as often as is necessary.

• Caution: If you're stirring the grain bed with the malt pipe lifted out of the BrewZilla, be very careful you don't accidentally dislodge it and have it fall back into the hot wort. It creates quite a mess and splashes hot wort everywhere. Ask us how we know.

6. Use a Coarser Grain Crush

• The way your grain is crushed can have a significant impact on how well water can flow through the grain bed.

• If you're constantly experiencing stuck mashes, try using a coarser grain crush. 

• A crush that is too fine will not leave enough of the grain husks in tact to aid with filtration and water flow.

Grain crush size can have a big impact on water flow through the grain bed

• If you mill your own grains, adjust the gap between the rollers so it is bigger.

• If your homebrew store crushes your grains, ask them for a coarser crush - they will typically know what type of crush will work for an all in one unit like a BrewZilla since they're so popular.

7. Just Add Water

• Try adding more water into the mash to help loosen up the grain bed.

• You can use some of your sparge water which may already be heated to avoid lowering the temperature by adding cold/room temperature water.

Conclusion

By following these methods and tips, you can effectively fix a stuck mash or sparge on your BrewZilla and ensure a smooth and trouble-free brew day. 

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