Gypsum Calc. Chloride Epsom Salt CaSO4 CaCl2 MgSO4 1.4 4.1 3 TRUE TRUE TRUE 2.0 5.8 4.2 12.75 before sparge stop sparge at 4.5 gallons
Based on boiling 12.20 gallonsliters at 1.043 for 90 minutes, this will decrease your wort by 1.50 gallonsliters, bringing your after boil OG to 1.048. You wanted an OG of 1.049. It looks like it will be under.