« on: April 23, 2013, 08:09:40 AM »
[...]2- sure you can do a 2.5 gallon boil and then top off with filtered or boiled and cooled water I would not use distilled water though as the mineral content in spring water is beneficial to the flavor and the yeast health. Just a FYI don't ever use reverse osmosis water though as it can kill the yeast as the osmotic pressure of RO water is higher than the cell wall of the yeast.
Are you sure about this? RO water is simply water that has been purified by being forced through a semi permeable barrier. Distilled water has less minerals than RO as it was evaporated and recondensed.
Regardless in an extract batch all those minerals are already in the extract and there is no need for more.