Mashing. Once the water is ready, pour about 3 inches worth into your empty cooler and shut the lid. This helps the cooler to heat up and reduces temperature loss. After about 10 minutes, pour all of your grain into the cooler and give it a quick stir. Pour in some more of the heated water until the water level is a few inches above the grain. Stir again, this time a little more vigorously as channels can form in the grain which will cause the water to not reach all the grains, thus losing out on a lot of the sugars. The grains should be saturated and move about freely at this point. Close the lid and set the timer for an hour. You can leave a floating thermometer in the mash and check to make sure the temperature is between 154 and 160 every 15 minutes, stirring each time. Keep a few gallons of water on the stove heating in case of severe temperature loss. You can also pour cold water in if it is too hot, but be careful, a little goes a long way and if you cool too much, you have to add more hot water. Usually, the cooler will hold the temperature for the whole hour. Until you get really good at this process, don’t worry, mild temperature fluctuations will not ruin your beer. Just avoid extremes.