This is a shot of the head space I had.
My point here is that there has been much discussion on head space in mash tuns, some say go with a 5 gallon cooler to minimize head space, others put a blanket on the lid, someone else mentioned putting foil on their mash to hold the temperature. I say none of that matters. I doubt very many people are mashing in as cold of temperatures as I do. And I only lost 1 degree in 2 hours in a very chilly environment. In my opinion if you are in the market for a cooler buy the 10 gallon one. That way if you ever decide you want to make a bigger beer you can. Or if you ever decide you want to go to 10 gallon batches it is one less thing you have to buy. Head space is obviously not a significant issue in maintaining mash temperatures.
