I see in the recipe he has a 5gal cooler for an MT. At 11.5lbs of grain, the cooler is about maxed out at 1.25qt/lb of water. He won't be able to add the 3+ lbs of grain to bring his OG up to what he wants, so he is adding DME to add gravity points. I do this with my big beers, and I call it a...