Have just purchased a 52 qt coleman xtreme to build a mash tun. In double checking calculations, based on actual measurements of the interior of this cooler, I'm finding that I'll probably only be using about 60-70% of the space (excluding the space taken by the manifold I have not yet built and considering ). (Looking at what I plan to brew, I'm seeing 12-13 pounds typically, max 15; 1.8 qts/pound) So, I'm now wondering if it's too big? Should I be looking for something smaller in attempt to use more of the volume of the cooler? Certainly not a bad thing to have more options for bigger batches or higher gravities, but I'm not sure if using only 60-70% is ok?