Thanks Netflyer. Now I have to look at how you got there. I hadn't thought of going that much distilled.
So with that much distilled water in the Mash Water should I also be concerned about the sparge water? Should sparge water be diluted the same as the mash? I've read that it don't matter, but it just seems to me if I need that much dilution in mash it would certainly make a difference in the sparge thereby final product. What about salts in the sparge?
My beer has been ok, but just not "right" I'm thinking it may be my water.
Funny you should ask... I believe we both use TH's spread sheet and I asked in another post (unanswered to date prob. cause only TH can answer and I should pm him) if when you make a dilution on the spread sheet does it consider the sparge water as part of the dilution?
So if we put 3.75g mash in with an 80% dilution representing only the mash portion of your total water I understand the sheet dilutes the mash. If we then put in the sparge water gallons, does that 80% also dilute that water by 80% distilled? If it does, then it seems to me there is no easy way the sheet can show us what 80 diluted mash with rec. salts + sparge with Your Water would yield in terms of final ppm. If the dilution does NOT include the sparge water then you can just put in the sparge amount and see the final results of each ion.
The reason so much Gypsum went in to this recipe was because you asked about meeting the Mosher recipe. The Morse recipe's Cl to SO4 ration was extremely low, like .14ish. On top of that the RA is low also. This was the sticking point with your water with your TA at 355. That is very high and makes it very difficult if not impossible to use your water to brew any light colored beer. The CaCO3 grabs H+ ions in the mash that if not grabbed could help lower the mash pH. Mg and Ca can help to strip the H+ out of the CaCO3 but only to a certain extent. When you start with or dilute with a good amount of distilled or reverse osmosis water you are diluting the CaCO3 (buffer) out and then the Mg and Ca can really bring the pH down and this allows for lighter color like you want.
Take a look at this graphic from Palmer's How to Brew chapter on brewing water. It's his nanogram that shows how adjusting the calcium ions up can lower the RA and the SRM. If you put your 355 in there in the middle you can see how hard it might be do drive that line that intersects through anything resembling a light colored beer.
So it seems the only solution to help you make anything but a very dark brew is to dilute. Also you could mess with the Cl to SO4 ratio, if you didn't want the pale ale to have that high of a ratio you could have used less gypsum and instead some CaCl2, probably less Epsom too both gypsum and epsom were used because you needed such a high SO4 level to meet that recipe. You could probably brew a very nice pale ale with a 1:2 ratio, what palmer considers bitter or 1:3 even. The Mosher ratio is much much lower.
So as far as salts in the sparge, since we really aren't sure yet about if the spreadsheet is giving us a diluted sparge or considering a sparge of the original water I'm not sure how to answer that ... TH's sheet will certainly tell you, if you leave those middle boxes checked, how much salt to add to the sparge water to keep the Entire water at the mash ion ratio... The question we both have at that point would be, 'Is this a desired condition'? I, just because Bobby_M showed me, like to use my water for the sparge and only add salts to the mash. But I have Very different water than you with a CaCo3 (Total Alkalinity) of 130 which is usable and manageable. So in your case you have 3 choices
1. Use distilled water for the sparge(s)
2. Treat the sparge water according to the ssheet
3. Use your water entirely for the sparge. (probably wouldn't hurt but someone else would have to help me confirm that since we're not exactly sure of the final ion concentrations)