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Small Grain Bill - Final Runnings SG Too Low


Grandmaster Brewer
Jul 6, 2012
Reaction score
Plain City, OH
I've created custom equipment profiles for each style I brew and so far everything has been working well - hitting gravity and volume targets pretty much spot on but the issue I am running into is with the gravity of my final runoff from the mash. I normally see 1.015 to 1.010 SG but on my Kolsch I see 1.002 or 1.001 SG.

My system is a 3-vessel E-HERMS with 10-gallon pots and I use BS2 for all my recipe formulations. My water is built up from RO. I run to a 7-gallon SSB unitank and generally like to fill it pretty full to take advantage of the chill coil which sits up pretty high in the tank, so most of my profiles are set to a 6.5- or 7-gallon batch size. I've used the same basic logic when setting up each custom equipment profile and they all work very well except for the Kolsch.

Not sure if it is a profile issue as I've carefully entered system losses where appropriate and again, it works quite well for all my other styles - just not the Kolsch. Granted most of my other styles use 13-15 Lbs of grain, and my Kolsch uses around 10 Lbs.

My initial thoughts are that I'm trying to pull the same volume into my kettle with less grain hence the low final runnings SG - looks like I am pulling too much water through the grain. But if I bump the grain bill up a pound or two, this just drives the OG up higher than desired.

Another thought is that I need to create a larger batch size for this particular style but that doesn't sound right because, I'd think, the software should account for the size of the grain bill and adjust volumes accordingly to get the right amount of wort into the kettle at the desired SG.

Because I am tightly controlling the water chemistry I am not having noticeable issues in flavor due to the low runoff gravities, but this is bugging me because it works fine for every style I brew - except for my Kolsch.

What am I missing here?

EDIT - As opposed to a potential software issue, could it be that for lighter styles, my mash is too thick? I shoot for 1.5 qt/Lb for every style I brew - should I be targeting a thinner mash for lighter styles?