Why did I get a low starch to sugar conversion? This could be due to a few factors; Incorrect grain crush Diastatic properties of the grain bill Incorrect mash temperature Wrong mash time Incorrect mash water pH Incorrect mash water calculations Mash thickness Related articles How can I improve my efficiency? Is the 'batch volume' the final, end amount I'll finish up with? What is BU/GU? I have a lot of foam forming during the boil, is this normal?