It's just ratios, the ratio of the water-mix compared to how much of that element is in the water.
Thanks Wolfy but i can understand that, but what I dont understand is what makes good brewing water for the beers that I brew, so if I was to dilute I would be still none the wiser to what is better, having a higher percentage of one mineral or a lower percentage of another,this is why I dialled it all in to Beer smith.
i have been reading on Braukaiser.com that he has a different water profile for each of his beers that he makes, I suppose what I am after is a water recipe one for dark beers and one for pale and one for lager but not sure how to go about this.
I think I am getting a bit above myself looking into RO water as I thought it was just a case of dialling numbers in to a calc and coming out with a suitable water recipe, I now see that just by adding dark malts I would be changing things quite a lot in terms of PH and other things, maybe i should just stick to what I know and be thankful my beers are OK,