I have struggled trying to calculate the amount of boiling water for a mash out. For those that use a round 10 gallon Igloo cooler as a mash tun, any suggestions on how many quarts of boiling water to add to raise the mash from 153 to 168 degrees, assuming 11# of grain and 13.75qts of water in the mash? In the past, I've done a similar recipe and used 8qts of boiling water, but my notes say that this only got the mash up to 162 degrees. This seems like quite a bit of water even when I try to take the thermal properties of the cooler into account. Thanks.