Add new oxygen absorber before finish old ones. Never re-use old oxygen absorbers.
EXAMPLE: Container of regular shape
Container of irregular shape Put the bag in water and measure the volume: Make up volume of water = 900c.c. Weight = 500g Oxygen in container(c.c.) = ( 900 - 500/1 ) x 0.2 = 80 c.c. * AGELONG S-100 or G-100 will suffice