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.
ReefCan features:
Slim & tall design that holds more RO water while taking up less floor space
Separate openings for the ATO pump cables and water refills
Transparent plastic body with an embedded water scale