Originally Posted by 400d
than what is the right ratio?
There is no "right" ratio.
"Standard" mashing for homebrewers is at about 1.25 qt/lb. That is what BeerSmith defaults too. 2.61 L/kg, if you switch to metric.
For English bitters, I like to mash at 1 qt/lb (2.09 L/kg), as this seems to give a more malty flavor (or so I am told). I'll also go down to this if I'm brewing a big beer that doesn't quite fit in my cooler at the standard ratio.
Higher ratios of 2 or even 3 qt per lb (4 to 6 L /kg) have been said to increase efficiency of the mash, and some people swear by it. More mash volume means less sparge water too, so you often only need one sparge and still get the good numbers.