150 QT Igloo Cooler as Mash Tun?


Oct 17, 2010
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Long Beach, MS
I have a huge 150 qt. Igloo cooler that measures 36" x 13" inside. I had planned to replace the bulkhead fitting with a ball valve spigot and pipe up a manifold of copper piping inside instead of making a false bottom.

I also plan to brew double batches (12 gal. +/-) which means my grain bills run between 25 and 35 lbs depending upon what I am making.

Now that I'm ready to get started I'm concerned that this cooler is actually too big to work with this grain volume. Since I'm pretty new to all grain and haven't brewed since last winter (too hot in my house in South Mississippi in the summer) I don't have a good sense for how much space that much grain will actually take up in the tun. If I'm not mistaken, I'd like to have a grain bed of 4"-6".

Any thoughts? 
Had a buddy using a 72 quart and it was way too big for 5 gallon batches.  He had trouble hitting strike temps.

that's what i've been using for 5 and 10 gallon batches. It was a little too full for 10 gallon batches of higher gravity beers. And it's now fallen apart thus my quest to find an alternative. Since I already have the big Igloo, I'm hopeful that it will work for 10 gallon batches.

Incidentally, when I refer to 10 gallon batches I really mean that I have about 12 gallons in primary and rack off 5 to secondary. So my volume in the mash tun is slightly greater than if I were to have only 10 gallons in primary.

I define batch size as how much I get to drink when I'm done!