With huge features jammed in a tiny package, the Duetto2 is the perfect ATO for your aquarium. XPAqua’s proprietary dual-optical sensor packs two precise level sensors in one incredibly small package. In addition to keeping your water level...

The ATK (Automatic Top-off Kit) is a simple, standalone, and complete solution for replacing water lost to evaporation. The new aquarium hobbyist has many challenges, but none is more annoying than the chore of adding water, every day, to make up for...

The Reef Breeders Prism-ATO  is designed to work with aquariums of all sizes, from pico desktops and All-in-One aquariums with limited space, to large reef tanks with full sumps. The Prism ATO has 3 sensors and registers your water level in a...

Sumpless ATO is the first and only ATO designed specifically for aquariums without sumps. The combination of the sleek overflow box and the innovative dual-optical sensor ATO will help to keep your aquarium topped off and your water crystal clear...