I have a Coleman Xtreme 70-Quart Cooler that I use for a mash tun and for batch sparging. I know that several others on the forum have mentioned using this same cooler (or one of similar capacity), and I am wondering if anyone has had issues with losing heat during the mash when brewing lower gravity beers with smaller grain bills. Overall, I am satisfied with this cooler’s performance, but am considering retrofitting it in some way to cut down on the excess head space when brewing with smaller grain bills to help with heat retention. I was thinking of possibly attaching a Styrofoam insert to the inside of the lid? I’m just curious to know if anyone else has dealt with this issue or found a simple solution.