Brewing with RO water

I`ve recently started using reverse osmosis filtered water for my all grain brews. When calculating salt additions (if any), is RO water close enough to ion free to neglect the mineral content, or do you think it`s worth the trouble to get it analyzed? Also, according to the nomograph on http://howtobrew.com ion free water should be the right pH for red beers, so if that`s what I`m aiming for is there any need to add salts? I think I read somewhere that calcium and magnesium is needed in the mash, but the malt already has plenty.

Bag O`Doughnuts wrote (not ion free as there will definitely be H3O+ and OH- ions). I believe RO alone will only be suitable for Pilsen, but then even Pilsen water has some minerals in it. The pH doesn`t dictate everything in the mash. If the red beer you want to brew happens to originally have pH 7, that does not mean that it is just as low in minerals as RO water. Mineral composition is far more important and if you want to copy a style, you should look at minerals more than at water pH. Having said that, mash pH *is* important just as, to my opinion (many here don`t agree) fly sparge pH water.
Calcium and magnesium are not plentiful in the malt as you suggest. Especially calcium is useful to add to RO water for both enzymes and yeast. Magnesium too, but you should actually look at the qualities you want in your beer to adjust the salts. Some tablesalt for sweetness and fullness, some sulfate for bitterness, etc. Or just copy a waterprofile that you know works well for a certain type of beer. This page http://howtobrew.com/section3/chapter15-2.html is quite revealing for how water can determine a beerstyle.
Make sure you have accurate weighing tools. Using the lower ends of scales doesn`t work well. If you don`t have accurate low-weight scales, you can always weigh a bigger amount, dissolve (homogenize if necessary) and dilute.

MDixon wrote promise I won`t rub it in if you get a (even) better beer.

me. As far as better beer, I won 27 ribbons at competition last year, came in third in NC as Brewer of the Year, and yes, I could make better beer, but I`ll be more than happy to put my beer up against anyones... www.ipass.net/~mpdixon/homebrew.htm

MDixon wrote make great beer. I was just suggesting a painless and easy experiment. No reason to start about runoff again, we know the difference in view there.

dilute.

Bag O`Doughnuts wrote so. All values under 10. It`s in the list.
Promash pH calculator is only impressed by Baking Soda and chalk. But forget that water pH. It`s water minerals and mash pH that count, and if your minerals will be as low as in Pilsen water, adjusting pH for sparge is of no importance either, as the grainbed will easily buffer it.

Bag O`Doughnuts wrote if you read it as Pilsen having that much Ca, it can`t be right. You can safely follow the Promash water list as a guide, even if on the net you may find slight differences for the mentioned waters.
The nitty gritty of pH effects of salts are not all that easy to grasp without some chemistry. My residual knowledge isn`t enough to be able to tell you clearly, neither do I know the English terms. What you can remember is, that if you`re very *low* in minerals, then even a rather high pH will be easily compensated by mash ingredients and therefore not worth a worry. If you`re high in -most importantly- bicarbonate ions, then the pH gets more muscle so to speak. But for the Pilsen you can forget about it as long as you keep the minerals as low as they should be for a Pilsen. Btw, if you don`t correct mash or sparge pH anyway, there is not much point in concentrating on it so much.