I brew from a blank slate so I'm not disparaging the launching of mineralized water from distilled or good RO, which is generally presumed to be close enough to a blank slate for most all practical purposes. What I am disparaging is at least twofold, as in my replies # 3 and 4 above. Lets review them, and add some more quandaries to ponder along the way.
1) Alkalinity is quite often detrimental to the mash, such that when it is present it is generally acidified to the degree that it is diminished or eliminated to where its negative influence can be forgotten. As such, adding alkalinity in the pursuit of duplicating a water profile is not necessarily a desirable or even sensible thing. But that might be the least of our worries, so on to multifaceted issue #2 (which could be broken down into more issues...).
2) I question the magic of duplicating mineralized water as to its true impact upon the final beer. I perceive that many brewers literally believe there is a mystical transcendence or magic of some form to be captured within brewing water, such that if they could only capture and duplicate waters magic they would be by some means transformed into master clone brewers. This I consider this to be a naive point of view of a magnitude similar to the once revered and now totally discredited magic of a mystical chloride to sulfate ratio. One reason for this being that mg/L or ppm measurements of mineral content do not scale to process variability. Let us initially presume only one ion, that of calcium. A book tells us that the magic required for a certain recipes successful cloning calls for 110 ppm of Ca++ (using your example in post #1). So the pursuit is on to discover how to get to this 110 ppm. And we discover several means to hit 110 ppm. But then other minerals are also mentioned as part of the magic, so we begin to juggle until we come to a "best fit" solution such as for the one you present in post #1, and independent confirmation confirms that it is indeed very close to nirvana. But then we realize that at least one of our materials, calcium chloride is an unknown as to its calcium and chloride composition. Unless this unknown becomes known we now realize that it is impossible to achieve a true 110 ppm, let alone juggle it with Cl and all of the other desired magical ion composition ppm's. But that aside, let's assume we have somehow hurdled this major obstacle and achieved the precise ppm's for all minerals within the magic water. Now what? If your reference source for the clone is like most recipes, the recipe only states magical water mineralization ppm's. Lets now look at two brewers, both reading and following the same book, albeit that there is one who mashes in water that represents 60% of the total volume of water and then sparges with the remaining 40%, and another who no-sparge mashes and thus adds 100% of the magical water all at once to the mash. Lets also realize, but for convenience initially again ignore, that multitudes of other mash water to sparge water ratios also exist whereby to make the cloned recipe. After ignoring again we are back to 60% vs. 100% water volume for the mash. The person mashing his equal in all other respects grist within 60% of the magical water, has added only 60% of the minerals to his/her mash vs. the 100% added by the other person. A 40% deficiency in minerals is present for this one from the basis of the other one presuming 100%, and a 40% overage of minerals is presumed for the other way of looking at it from the perspective of 60% being right. Thus the magical quantity of minerals required to transform the grist into spectacular cloned beer has the potential for massive over or under mineralization error in the reaction or interaction of the grist with the minerals for both brewers. And now we remember that a virtual infinity of other ways to mash and sparge with respect to water volumes lie between our two extremes, and also outside of our two extremes (as would be the case for someone who mashes in 50% of the requisite overall water volume and sparges with the other 50%). Yet both brewers following the magical clone recipe are unlikely to think this way, believing only in the books advice that a specified water with magical ppm's of minerals, when duplicated as close as is possible, will lead each brewer to cloning nirvana. How is such nirvana possible for the case of potentially being 40% over or under mineralized (or more)?