I'm brewing 2.5 gallon batches and I use a 5 gallon Igloo water cooler for a mash tun. When I was cleaning up, I filled the cooler with cold water to cool the grains down. Just on a whim, I got the hydrometer out and took a reading of the cold grain mix. I got a reading of 1.004.
Here is my question. I realize I'm not ging to get ALL the sugars out of the grains, but I was kind of surprised there was still that much sugar left. Or, would that be a 'normal reading' and I'm seeing a problem where none exist?
If anyone has any insights, I would be grateful. Thanks.
[/quote]
Regarding your question about gravity after mixing water with the spent grains; if you filled the cooler with water, I would guess that's a pretty high reading as you must have diluted the grains with maybe 2 or 3 gallons of water. That said, it is common to take gravity readings toward the end of the sparge (undiluted runnings). The final runnings should not be allowed to go below 1.008 as below this point tannins can be extracted from the grains creating astringency. Above this point you are loosing efficiency. A few points higher will not have much effect on efficiency but in my experience with light Belgians, lower will create astringency. I try to stop my sparge anywhere between 1.012 and 1.008. Also, the pH of your final runnings should be below 6.0 to avoid astringency.