Regardless of your Grainfather Brewing Unit, if you have a stuck mash see below:
- If liquid does not flow through the grain, then you have a 'stuck mash': To test this, stop the pump and see if the wort level on top of the grain bed drops. If the wort level does not move, then this is a 'stuck mash'.
- If the wort clears slowly, then you have a 'slow mash',
- To fix a slow or stuck mash:
- Give the grain bed a gentle stir with your paddle;
- Consider adding 1-2 handfuls of rice or oat hulls to your mash. If you don't have these on hand,. uncrushed barley malt will work, though it will add some colour and may add a small amount of fermentable to your wort;
- Be wary that a slow mash will decrease efficiency, therefore you will want to increase your mash time to be on the safe side. We recommend increasing your mash time by 1/2 hour OR do a starch test to ensure mashing has completed.
If you don't fix a stuck mash it will likely lead to a stuck sparge.
To help ensure that this does not occur in a future brew session, look to increase the gap size on your mill to decrease the crush, if this is not possible (due to you not crushing your own grains) look to consistently add some hulls to your grain bill instead, to avoid stuck mashes.
A stuck/slow mash is likely caused by a large portion of the grain bill being powdery or too finely crushed.