The ReefCan 18 and ReefCan 40 can supply the ATO of a 50-gal or 130-gal tank with enough RO water for about a week. They can fit in the sump cabinet or behind the tank, can be refilled without having to remove the reservoir and disconnect its tubes & cables, and have a transparent plastic body with an embedded water scale that allows you to see how much RO water is left.
