ive tried using beersmith, brun water, and ezcalculater but still need help clarifiying it for me...
My Local water is as follows
A. Profile (Ca ppm) (Mg ppm) (Na ppm) (Cl ppm) (SO4 ppm) (HCO3)
49 14 45 55 18.5 191
getting different additions totals from the 3 different programs... should i just use distilled water and build my own water or try using my local source??
There are a couple of reasons for variability in the answers one gets when trying to match a particular water profile by adding salts to RO or tap water. First, none of the programs you mentioned handles the carbonic acid/bicarbonate/carbonate system properly (and you can add Brewers Friend to that list) and second and none except Beersmith tries to find an optimum match (and Beersmith bobbles it because its basic water chemistry is flawed). Third, even if you do use an optimizer there are, in many cases more than one solution (answer) that are 'pretty good'.
Yes, you should... and the main reason is that 191 HCO3 is high alkalinity.
Not to pick on McKnuckle here in particular but a flaw shared between these calculators seems to be that they assume just what the quote says (I bolded is). Bicarbonate is the major
source of alkalinity as long as the water's pH is below about 8.6 (which it is most of the time but not always). Below 8.6 and as long as the alkalinity is above 25 ppm as CaCO3 bicarbonate can be calculated from alkalinity by
bicarbonate = 61*alkalinity/50
and the error will be within ±3% which isn't too bad. At alkalinity of 12.5 the error is 10 - 15% but that means 1.25 - 1.9 alkalinity units so we don't care. Above pH 8.6 hydroxyl ions contribute appreciably to the alkalinity and the approximation can induce errors of up to 40%.
Up to this point we are talking about finding out what you need to add to RO or other water to produce a given profile. Because none of these 'water' programs seem to recognize that adding acid or base or bicarbonate to water will cause its pH to shift one cannot really use them to match one water to another.
The other application to which these programs are put is estimating mash pH. Each models the properties of the malts the user specifies in different ways and this is, of course, behind quite a bit of variation and combines that with the properties of the water you feed it. As each uses different models for the properties of the malts they are all going to give different answers and they seem to more or less correctly handle the shifts in mash pH caused by alkalinity in the water. I think this is perhaps because they recognize that strong acid cancels base and even though the alkalinity of the carbo system is not always accurately calculated the approximation is usually pretty good and when it is bad the actual level is not large relative to the alkalinity of the malts.
None of these calculators (including Brewer's Friend) give you complete guidance as to what to add to tap water to reproduce Pellegrino (as someone is trying to do in another currently active thread) but they won't tell you what to add to RO water either. But if you restrict your additions to neutral salts (sodium chloride, calcium sulfate, magnesium sulfate, calcium chloride but not sodium bicarbonate) they will correctly calculate the concentrations of sodium ions, sulfate ions, etc.
There are lots of good reasons to use RO water. In this particular case we can't say what the actual alkalinity is but it is most probably close to 50*bicarb/61 = 156 ppm as CaCO3 i.e. about 3 mEq/L and that's a pretty compelling reason though there are other ways to handle it. For example if you would like to have sulfate at about 165 and you could get food grade sulfuric acid you could just add 3 mEq/L sulfuric acid to the tap water. Alkalinity, and the bicarbonate that caused it, would be gone.
If you want to brew using RO water you still have to figure out how much of what salts/acids to add to it to get the mash properties you want. You will get different answers from each of the 4 programs but they shouldn't be too different. You shouldn't totally rely on any of them (all though many do) but rather use them as guidance. You'll see lots of posts here about how Meister Water always gives me great results and how Narr Water is always high (or low) and lots of reports about how Meister Water was way off and Narr Water was spot on. If you find, in using one of the programs, that it gives good results that probably means that it models your type of brewing well. Stick with that one.
You don't really have much of an alternative except to take the KISS approach to using RO water as described at
https://www.homebrewtalk.com/showthread.php?t=198460 or to learn the chemistry (it's at
https://www.homebrewtalk.com/showthread.php?t=473408) and write your own spreadsheet or program. I'm glossing over just a few details here, of course. The chemistry really isn't that complex. It only took me 15 yrs to figure it out but a real chemist should have no problem.
