Salts CaSO4 3.2g CaCl 2.0g plus a quarter tab campden. 1.5g whirlfloc G and 2.2g yeast nutrient added at 10 min boil.
Based on boiling 7.00 gallonsliters at 1.038 for 30 minutes, this will decrease your wort by 0.50 gallonsliters, bringing your after boil OG to 1.041. You wanted an OG of 1.051. It looks like it will be under.