IceCap Gravity ATO — Non-Electric Nano Auto Top Off (IC-GATO)
The IceCap Gravity ATO System (SKU: IC-GATO) is an authentic, completely mechanical water management device distributed by CoralVue to preserve environmental stability in compact nano aquariums, desktop freshwater displays, and miniature saltwater frag grids. Evaporation is an unforgiving enemy in small-format setups; because the overall water column volume is tiny, losing even a few ounces of fresh water causes a rapid surge in salt concentration, straining sensitive corals, decorative shrimp, and small reef fish. While automated electronic systems are great for larger show tanks, adding bulky magnetic optical eyes, wires, control modules, and secondary feed pumps to a micro desktop tank creates unnecessary visual clutter and physical hazards. The IceCap Gravity ATO resolves this by condensing your top-off requirements into a single, power-free mechanical bracket.
The system utilizes basic principles of physics and atmospheric pressure differentials to self-regulate. When screwed together and seated onto your tank rim, two custom-trimmed silicone tubes extend down into the water column—one cut slightly shorter than the other. Under standard operation, the water line covers both tube tips, creating a structural vacuum seal inside the inverted 500ml reservoir bottle that holds back the fresh top-off water. The moment evaporation lowers the aquarium's surface line to expose the tip of the shorter tube, air breaks the vacuum boundary and bubbles upward into the bottle. This pressure equalization immediately allows a corresponding amount of fresh RO/DI water to slip down through the longer tube, raising the water line until both openings are safely submerged again. Simple, efficient, and highly dependable, this system keeps your micro ecosystem perfectly balanced.
Key Features
Eliminates Electronic Failures: Free of moving mechanical components, magnetic sliders, or circuit boards that can fail from salt spray, mineral scale, or temporary house power grid failures.
Simplifies Maintenance Routines: Eliminates remote reservoirs, loose under-cabinet plumbing lines, and wire management paths—simply unscrew the bottle, refill it with fresh RO/DI, and thread it back in.
Tailored Elevation Setup: Slanted tube tips allow you to fine-tune the high-water threshold to accommodate the unique wave action or water level requirements of your specific display.
(Note: This self-contained nano top-off setup includes the primary Gravity ATO base hub, 3 rim-gap sizing inserts, a 500ml water bottle, and silicone tubing lines. Replacement bulk tubing is sold under separate product categories).
