Low OG Question

Rwaterman82 · 05-17-2011, 09:36 PM

This weekend I brewed my second AG batch. The brew day overall went well however I was very disappointed with my OG.

Let me start by saying the first AG batch I brewed also had low OG (Recipe 1.057; Actual 1.047) but as I dug out the grain from the 48 QT cooler I noticed the manifold had come loose and allowed the grain to channel through the outlet hole and not the manifold. I thought this was the cause and made modifications so this would not happen again.

So when I brewed my second batch, a Stone Ruination Clone, I thought I had the problem solved, but come to find out, I had an even lower OG (Recipe 1.086; Recipe 1.070). The mash temp was held consistently through 90 minutes between 151 and 153. Mash was mixed every 20 minutes to make sure there were no hot spots.

My first runnings gave me a gravity of 1.082, batch sparged, then second runnings 1.052 and a mixed gravity of 1.066. After a 90 minute boil i came up a little short on 5 gallons so I added an extra quart and a half of water, mixed and got a OG of 1,070. All readings were taken with hydrometer @ 60 degrees. I am using filtered tap water.

My LHBS owner can tend to be a space cadet, could he have stiffed me some grain lbs by accident?
Could i have bad pH in the tap water? Would this cause this issue.(Have not been checking to date)

**BigB** · 05-17-2011, 10:13 PM

You will find hundreds of posts on this subject. But my first thought would be the crush of the grain. Usually LHBS's don't crush fine enough. If they are using a real grinder (not a Barley Crusher with a cordless drill), ask them to tighten the gap setting for you. If you are crushing your own and can adjust the gap, start at .045. And yes, mash PH can have some effect on efficiency as well. You could probably get an idea of your tap water ph from the municipality, and then using some calculations for your recipe you could figure out what your mash ph is. Or, try using some 5.2 buffer.

**Yooper** · 05-17-2011, 10:21 PM

If your second runnings were 1.052, you still had PLENTY of sugars in the MLT left behind. I would suggest sparging more (especially since you were short on your boil volume) and sparging in two batches.