Originally Posted by Piotr
I don't understand, why can't I just add salts for the 7 gallons of preboil volume from the beginning of the mash
Many of the salts will dissolve in distilled water. Once they're mixed in the mash and the ph starts to drop the salts will dissolve.
I usually use about 9-10 gallons of water for a standard 6 gallon end of boil batch. It I mixed all the salts and water ahead of time some of the salts would drop out and never make it into the mash.
No real need to mix the salts into the sparge water as the ph of distilled water should settle out to an acceptable level for sparging without the salts.