Water Profile pH

I'm giving the BeerSmith2 water profile tool a shot with my next batch.  In Ingredients -> Water -> Add Water it asks the pH for the water.  Am I expected to put in the pH that I WANT for that water profile I'm creating, or the pH of my existing (in this case, RO water) water that I will be using?  I assumed I put in the pH that I want to have and that transfers over to the Mash tab where it helps calculate a Lactic Acid adjustment..  IT doesnt seem to make much difference on the Mash tab when I play with the numbers, but I guess I'm a stickler for understanding the details.

Thanks!

When you are filling out the water profile, you want to enter the actual pH reading of your starting water.  The program uses this to figure out the ability of the minerals in the water to buffer changes from malt, acid, or salt additions you make to it.

Then in the water profile tool, you can add the minerals to the water to get the mineral profile you want and save that as the target profile. 

On the mash page, you can enter in your measured pH of the wort after doughing in and make an adjustment by the addition of acids.  I would take the recommended adjustment with a huge grain of salt (no pun intended, maybe) as others have reported that the calculated amounts of acid to add are 2x to 5x too high.  In my own case, the impact of acidulated malt is generally about 10x what I actually add to my system.

Which is another point about the water profile tool as it is right now.  To have any mineral additions be used in the recipe calculation, you need to "add water" on the design page and add the water profile and the associated salts to the recipe.  Adding water salts independently will not have any effect on the pH calculation.  Likewise, any addition of acid malt or acids on the design page do not impact the estimated pH calculation.

Wow, now I am really confused.  Sorry for being so dense on this subject.
I updated my local water profile based on the water companiy's latest report.  The pH level used to be okay, but it went up to 8.1 in the latest report. When I printed my "brew steps" for my last batch, it had a bullet point for "Mash Water Acid:" but nothing after that.  In fact, this was the ONLY place on the program that it mentioned "mash water acid".

So, my question is, do i need to purchase an expensive pH meter to continually measure pH; and, at what stage in the brewing process do I measure it?  Before I start?  In MAsh tun?  In brew pot?

Thanks. ???

Don't feel bad about it, even water 'experts' such as A.J. DeLange and Martin Brungard get into disagreements on water chemistry.

First, you are saying that the pH reading on your water report is different from the last report?  OK, don't sweat it.  The pH of your base water only has a minor impact on the buffering capacity of the ions in the water by determining the form the carbonate ions are present in. 

Second, the comment about the mash water acid appears in every brew sheet printed.  It is in the base HTML in which the report is written.

Next, your water profile only impacts the prediction of mash pH in BeerSmith IF you have entered your water report as a profile in the water ingredients and IF you have added that water profile to the recipe as one of the ingredients.

Now, if you are doing all-grain brewing and want to endure better efficiency from your grains, you would be on the right track to get a pH meter and measure the pH of the mash.  The (arguably) best place and time to measure the pH is about 15 minutes into the mashing, at the draining of the first runnings and at the end of draining the sparge water.  An alternative to the pH meter would be pH test strips.  They work OK do not have the precision of a meter in most cases. 

The reading at 15 minutes into the mash it to make sure you are within the desired range for best conversion [5.2 to 5.6].  At the end of the mash, the reading is to ensure you are still within that range, as the pH will change based upon the minerals in the malts and the types of malts in your grain bill.  If you are doing a fly sparge, many brewers will check the pH of the run off to ensure it does not go above a pH of 6.0 as the combination of high temperatures (above 170?F+) and high pH will help in the release of tannins from the malt husks.

While there is some confusion about the actual measurement temperature, the correct method is to take a sample and chill it down to room temperature and then take the pH reading.  While pH meters will come with ATC or 'automatic temperature correction,' this is often mistaken for correcting the pH to room temperature.  The correction is actually a correction on the electronics inside the pH meter to the calibration curve of the probe to negate the effect of high (or low) temperatures on the slope of the calibration curve.

You don't necessarily need to invest in a high priced pH meter, though those are much more reliable.  I would recommend getting a model with automatic calibration, though.  Models where you need to calibrate the meter manually using a screw are often difficult for those who don't know how to make the adjustments and unreliable in holding that calibration.  Even then, I would look at a pH meter which costs less than $40 or so as a disposable piece of equipment, needing to be replaced every year or so when it becomes difficult to calibrate.  Even with expensive pH meters you will need to replace the probe on a similar basis.  I've been using the same $20 model for about a year now and it is working fine.  I do need to calibrate it every time I use it though as it does drift quite a bit.

Once you have a handle on what your mash pH is in some cases, then you have a chance to learn how to modify it to change the pH of the mash and accentuate flavors in your recipes.  I highly recommend looking at some of Brad's blogs and interviews on water chemistry and reading Martin Brungard's primer on 'water knowledge' which can be found on his web site at https://sites.google.com/site/brunwater/.