Ascaso In Tank Rechargeable Water Softener / Particle Filter for Espresso Machines - 24 L (D107) Resins are rechargeable for up to one year (recommended to recharge at least once or twice a month with salt OR every 24 liters of water) Can be used in all pump model espresso machines that have a water intake tube in the espresso machine's water tank (this cannot be used in espresso machines with direct water/plumbed in connections or where there is a bottom feed of water from the reservoir) Depending on your monitor, the resins may look lighter or darker than what they really are.