I've got questions. I usually make 10 gal batches, with maybe 22-24lbs of grain. This fits nicely in my 80qt Coleman Extreme. I usually mash at 1.75 - 2.0qts/lbs, which lets me collect about 8gals first runnings, then I sparge with about 8gal and collect the 16gal I need to boil down to 11gal (I have a huge steam kettle with large surface area that loses a lot to evaporation.)
Sometimes I do 15 gal batches with 30-35lbs grain, in this case I mash at about 1.5qts/lbs so it fits in the cooler, and then I can still get pretty good efficiency even though first and second runnings are not totally equal. I collect about 23gals and boil it down to 16gals of post-boil volume.
Now I want to do a 20 gal batch which will use about 45lbs of grain. It will not fit in my mash tun unless I start mashing thicker, like 1.3qts/lbs, and then I will have to add a lot of sparge water (maybe 16+ gals) to get my 26gals of pre-boil volume.
So the questions are:
1) Will my efficiency or process suffer somehow with mashing at 1.3qts/lbs, as opposed to the thinner 1.75-2.00qts/lbs that I’m used to, and that my recipes work for?
2) If not, can I go ahead and mash with the highest ratio that still lets me fit the mash in the mash tun, and then split my batch sparging into 2 parts? Should these parts be equal volumes? Does it matter?
3) Or should I just add as much sparge water as I can when starting the second runoff, and then just keep topping it off until I’ve added what I need?
Thanks in advance for any advice. I know I could avoid all this with a bigger mash tun but I don’t plan to do 20 gals batches that often.