Lactic Acid....How Much!!

I'll be doing my first all grain this weekend. EdWorts Haus Pale Ale. I have my mash water chemistry dialed in using Beersmith and EZWater Calculator. But I'm not sure how much lactic acid (88%) I need to add to my sparge water to get the pH down to around 6. I'll be double batch sparging with about 5gallons of water. I have pH strips and plan to check my sparge water after adding my lactic acid to see where I'm at. Just trying to get a starting point of ?mL. Thanks!!!

pH 7.6
Total Dissolved Solids (TDS) Est, ppm 211
Electrical Conductivity, mmho/cm 0.35
Cations / Anions, me/L 4.0 / 4.1
ppm
Sodium, Na 3
Potassium, K < 1
Calcium, Ca 51
Magnesium, Mg 16
Total Hardness, CaCO3 194
Nitrate, NO3-N 1.3 (SAFE)
Sulfate, SO4-S 4
Chloride, Cl 5
Carbonate, CO3 < 1
Bicarbonate, HCO3 221
Total Alkalinity, CaCO3 181
Total Phosphorus, P 0.59
Total Iron, Fe < 0.01

Bru'n Water has all the answers you're looking for.

Simple enough. Thanks!! I've poked around with brun'n water, but forgot about the sparge acidification section.

Appreciate it.