"Pool Shock" is calcium hypoclorite. IIRC the 50% strength ratio is 1 pound to 5,000 gallons.

Be careful with it - its flammable / explosive (the dust under compression can KB) and a corrosive. It also degrades under heat, and can be unstable.

greaser,
Household bleach loses 50% of its strength after six months at 75F storage.

Pool Shock will last longer because its a concentrated solid (not a diluted liquid like bleach).

EDIT: Bleach is Sodium Hypochlorite. There is one molecular difference between the two products. The main difference is the concentration of the purifying properties and shelf life.