I found this thread, because I am looking to make myself an MLT as well. My biggest concern, on top of maintaining mashing temps, is having a good grain bed. I'd like to make sure that for any of the 5 (or 10) gallon batches I make, I have at least a grain bed depth of 4 inches to ensure good sparging. I'm thinking that 10 pounds is a realistic, minimum grain bill to consider (any smaller and I'll just use a stovetop method). Is there some way to know if a 10 pound grain bill will give me at least 4 inches in my grain bed?
EDIT:
After a bit more research and thought, I have done the following calculations. Based on
this link, the volume of 10 pounds of grain at a mash thickness of 1.25, the mash would take up 3.93 gallons (907.83 cubic inches) of space. The OP posted a link for a cooler with dimensions of 31.5in L x 16 in W x 18.25 H. If you subtract 2 inches (approximation) for wall thickness, the approximate interior footprint would have an area of 413 in^2. 907.83 cubic inches divided by 413 inches squared yields 2.198 inches of depth. Furthermore, this depth includes the 3 1/8 gallons of strike water. The grain bed is going to be notably less than 2 inches. If you plan on batch sparging, you really should have at least 4 inches of grain depth for an efficient sparge (based on my reading, namely John Palmer's How To Brew). Even for a 10 gallon batch of this same gravity, the size of this cooler would be debatably too large. I'd say that for a brewer looking to do 5 and 10 gallon batches, this cooler is too big.
Based on this and other research I've done, I'm strongly considering the cooler recommended by mr tripp here :
Would this cooler be better:
Igloo 60qt Ice Cube
I saw the other thread on how to convert this.
This will be good for 5 gallon batches of OG greater than 1.065 and 10 gallon batches with an OG less than 1.100. For anything smaller than 1.065, I can do a stovetop method. And if I'm really brewing 10 gallons of anything larger than 1.100, I suppose I'll just have to do two 5 gallon batches.