Ask Mr. Wizard

Curing Sparging Woes

TroubleShooting

Mark Connell — Bedford, Massachusetts asks,
Q

I have been making a pumpkin ale for the last 7–8 years. Because I put flaked oats into the grain bill, I have always used rice hulls to prevent a stuck sparge; however, 3 out of the last 4 batches, my first runnings and sparge have been very slow. During my last batch, it took an hour to get almost 2.5 gallons (9.5 L) using 7 gallons (26.5 L) of strike water. I sparged with another 5–6 gallons (19–23 L) of water and it took almost an hour to collect as much as I could. In the past, it has taken longer than other styles to collect wort but not this long. Could I possibly be using too many rice hulls on the bottom of my mash tun? I put the rice hulls on top of my false bottom and mix into the grains. I use a 10-gallon (38-L) water cooler as my mash tun. Grain bill: Pale malt, Caramunich® malt, Munich malt, caramel 40L, flaked oats, white wheat malt, and Victory® malt for a total of about 13 pounds (5.9 kg) for A 5-gallon (19-L) batch. My last batch was double. I also put about 30 ounces (850 g) of canned pumpkin in the mash.

A
The likely culprit to this problem, assuming that you have been using the same basic recipe over the last 7–8 years, is beta-glucan from the flaked oats. I am betting on this
Response by Ashton Lewis.