BDP wrote:Still got another OG reading less than expected, but as posted previously, I now strongly suspect the coarseness of the grind. Will have to invest in my own mill, as my supplier does not allow patrons to adjust the grind on their mill.
It won't be coarseness of the grind BDP so don't waste money and time on a mill at this point.
Even if you have come across this list on the forum before,
double-check it because I have just added three new points...
[center]
Some Common Reasons for a Low Efficiency Reading[/center]
1. Reading has not been confirmed. (This
table shows the resulting measurements of 30 brewers mailed identical ingredients and then asked to brew the same recipe.)
2. Grain bill incorrectly weighed.
3. Thermometer not calibrated at mash temperatures. (This
post shows how unreliable a single thermometer is.)
4. Hydrometer not calibrated at original gravity* (or the brewer is taking gravity samples that are too hot to temperature correct.)
5. Bag is too small and restricts liquor flow. Your BIAB bag needs to fully line the kettle.
6. Bag porosity is too small. 35 vertical and horizontal threads per cm works well.
7. pH of mash has not been adjusted.
8. Estimated mash efficiency did not reflect the gravity of the brew. (A high gravity beer will have a lower mash efficiency than a low gravity beer. NOTE CAREFULLY: This point can be ignored if you are using the BIABacus as the BIABacus adjusts for gravity.)
9. The brewer is measuring 'efficiency into fermenter' rather than 'efficiency into the kettle.' The first figure is often far lower than the second.
10. The grain used has lower extract potential or higher moisture content than the specifications being used for the calculations.
11. Mash time is too short. In full-volume BIAB, mashing and sparging occurs simultaneously. Pulling your bag at 60 minutes, cuts this process too short. Allow at least 90 minutes and preferably follow with a mash-out.
12. The grain is not being agitated during the mash. Time, temperature and agitation are how we 'wash' things. Agitating the grain and checking the temperature several times throughout the 90 minute mash has no downside and should be done so as you can determine the cost of not agitating.
13. Grain crush is too fine or too coarse. Ensure most grains are broken or squashed, not pulverised. See
here.
14. You are incorrectly measuring volumes. Use your kitchen or bathroom scales and sections B and U of the BIABacus to check your volumes by weight. (One litre of water at ambient temperature = one kilogram.)
15. If buying your grains pre-crushed, age can affect efficiency. For example, crushed grain, stored in a humid environment will become heavier as it sucks in water. The grain becomes heavier but the sugar content, by weight, reduces.
* Check your hydrometer at 1.050 by dissolving 130 grams of table sugar in about 0.9 litres of hot water. Let that cool to 15 C or 20 C depending on your hydrometer and then top it up to 1 litre and take your measure.
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the above or anything else of value on BIABrewer.info, consider supporting us by
getting some BIPs!
. I was probably drunk but what's everyone else's excuse? 
. (Or a single reading 
