Water Preparation
Like most brew days, we started off by collecting our water. 23L strike water for the BrewZilla, and 12L of sparge water in our Digiboil. The recipe only called for around 8-9L of sparge water but we always like to have a little extra
We then measured out our additions of calcium chloride and calcium sulphate to reach our desired water profile - both the strike water and sparge water were treated.
We also added some phosphoric acid to the strike and sparge water.
We got the sparge water treated to a pH of 5.25
Grain Preparation
Next, we measured out the grain to be used in the recipe - a mix of regular 2 row (ale) malt, oats, wheat malt, and some gladiator (dextrin) malt.
We then milled all the grains (except for the oats) and started mashing in.
First Mash pH Reading
After mashing in and leaving the grain bed to settle for about 10 minutes, we took our first sample for a pH reading.
At 5.34 we were well within the desired 5.2 - 5.6 range, however we wanted to get a little closer to 5.2.
We added another 1mL of phosphoric acid which barely made any difference, so we then added another 2mL on top of this, followed by another 1mL which got us to 5.22
The Mash
We began recirculating our wort with the sergeant sparge head and got pretty decent flow through the grain bed for the 60 minute mash duration.
We did discover that the RAPT Temperature Probe we normally use was reading a few degrees low after double checking with a second thermometer. We maintained the target temperature of 67°C for 60 minutes before ramping up to 75°C for a 10 minute mash-out period.
Sparging
After the 10 minute mash out we lifted the grain basket and began sparging until we reached our desired pre-boil volume in the BrewZilla (28L). Like with the mash recirculation, the flow through the grain bed with the sparge water was good - no stuck sparge so was completed in around 10 minutes or so.
Pre-Boil Gravity Reading
Our first gravity reading came in at 1.045 - a single point higher than expected from the recipe. We did lower our brewhouse efficiency from 75% to 70% as we know from experience that when using oats in the grist we get a slight drop in efficiency.
The Boil
Plenty of hot break when the boil got underway, which was largely uneventful. Only a couple of hop additions, along with some yeast nutrient and whirlfloc. Even though it's a hazy style, we decided to use a whirlfloc anyway.
Post-Boil
At the conclusion of the 60 minute boil we chilled the wort slightly to around 85°C before whirlpooling for 15 minutes (without any further hop additions). We then continued to chill the wort using our immersion chiller.
Due to the relatively warm ground water, we got the wort into the high 20's (°C) then transferred to the fermenter and put it into the fermentation fridge to allow it to chill further overnight to the target fermentation temperature of 22°C.
Our post-boil gravity reading came in at 1.052 - a little higher than expected, especially considering the pre-boil gravity so it's possible one of these readings was off by a point or two
The following morning when the wort had cooled further, we pitched a single packet of Fermentis S-04 yeast, and saw fermentation was underway within 12 hours.
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