Question regarding TH's spreadsheet

I want to make sure I'm using the distilled water dilution rate correctly. I was using the brewater program and it's nice, but TH's spreadsheet is much more user friendly.

My water profile:

CA - 69.2
MG - 48.7
SO - 9.9
CL - 1.5
NA - 3.3
Alkalinity - 345
Hardness - 377
PH - 7.59

In brewing my APA I typically take 3.0 gallons of our water and dilute it with an additional 1.5 gallons of distilled water for a total of 4.5 for the mash. I then also take 1.0 teaspoons of gypsum and .5 teaspoons of CaCl which gives me a mash water profile of:

CA - 127
MG - 25
SO - 128
CL - 73
NA - 1.6
Alk - 173

Now, in my head that is a 33% dilution. However, when I plug all of that in and utilize a 33% dilution in TH's spreadsheet I'm coming up with:

CA - 148
MG - 33
SO - 162
CL - 68
NA - 2

Anyone wanna take a shot at what I may be doing wrong with the spreadsheet? Am I using the dilution section incorrectly? All told, it looks like a good profile for what I am brewing so that's good I guess

Thanks ahead of time.

The way the formulas work, it appears that dilution rate is defined as distilled water volume divided by starting water volume, so 1.5 gal / 3.0 gal = 50%.

I have 4.5 input in the mash h2o volume and 33% input for dilution so I don't think that's it. I wonder if the brewater calc is looking at it differently than I thought it was. I use 3 for gallons treated and 1.5 for gallons dl when using brewater. Check that, I just tried brewater with 4.5 for gallons treated and 1.5 for gallons dl and I get a whole different set of numbers.

Sorry for the confusion, just want to get this right so that I'm good to go going forward.

You're using the dilution factor correctly, but you're screwing something else up.
If you start with your original profile, dilute with 33% distilled water, and forget any salt additions, you should end up with:
Ca = 46
Mg = 33
SO4 = 7
Cl = 1.5
Na = 2

What weight to volume calculations are you using?
According to Palmer, 1 tsp CaS04 weighs 4 g, and 0.5 tsp CaCl weighs 1.7 g
Adding those weights of salts in, you should get
Ca = 127
Mg = 33
SO4 = 138
Cl = 49
Na = 2

Adding gypsum (Ca and SO4) and CaCl (Ca and Cl) will not affect the Mg in any way, yet your second listing shows that the Mg has reduced from 33 ppm to 25 ppm.
I doubt that that would make any noticeable difference, but the source for your second listing is undoubtedly wrong.
When it comes to the third table, your Ca, and SO4 are both high, which would indicate that the weight of 1 tsp of gypsum is assumed to be > 4 g
The good news is that the differences are really insignificant.
The bad news is that if you want to get is right, you cannot rely on volume measurements. You have to rely on weights.

-a.

Thanks AJF, I really appreciate you taking the time to figure that out. I was using an online calculator to convert teaspoons to grams. I believe it was telling me 1 teaspoon weighs 4.55 grams or something along those lines. I'll have to double check when I get home from work. Should have been using Palmer's book from the get go. Didn't even think about grabbing it when I was playing around with the spreadsheet last night.

cp

AJF - How do you typically measure your additions (teaspoons or grams)? I have always used teaspoons as it just seemed easier. If you measure by gram what type of apparatus are you using to do so?

Thanks again for the help.

cp

I have a lot of problems with using teaspoons etc to weigh small amounts, so I use a 1/100th gram scale. http://www.gramscales.com/product_info.php?cPath=24&products_id=290
I find the scale easier as you don't have to worry about how compacted the volume is.

-a.

Thanks again, really appreciate it.