Salts CaSO4 3.2g, CaCl 2.0g plus a quarter tab campden. Pitched a white labs pouch directly after chilling before sticking in the fridge at 10C.
Based on boiling 7.00 gallonsliters at 1.048 for 30 minutes, this will decrease your wort by 0.50 gallonsliters, bringing your after boil OG to 1.051. You wanted an OG of 1.053. It looks like it will be under.