Red Sea Desktop ATO

The Red Sea Desktop ATO (Auto Top-Off) is a compact, easy-to-install auto top-off system designed for the Red Sea Max Desktop aquarium and other nano reef setups. It automatically replaces evaporated water to keep your tank's salinity and water level stable — no more daily top-ups, no more stressed livestock.

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• Automatically maintains a consistent water level
• Keeps salinity stable — critical for reef tank health
• Direct fit for the Red Sea Max Desktop aquarium
• Optical sensor detects water level accurately without moving parts
• Compact footprint — fits in the filtration compartment
• Reduces daily maintenance workload

What is an ATO and why do I need one?
An Auto Top-Off system replaces water that evaporates from your aquarium. This is especially important for saltwater tanks because salinity rises as water evaporates — a stable water level means stable salinity and happier livestock.

Is this only for the Red Sea Max Desktop?
It's a direct fit for the Max Desktop, but the optical sensor and compact design let it work with many small reef and freshwater tanks. You'll need a reservoir for top-off water.

How does the optical sensor work?
The sensor uses light refraction to detect water level — no moving float, nothing to jam or fail mechanically. It triggers the pump when evaporation drops the level below the set point.

Do I need a separate pump?
Check the included components — the Desktop ATO system typically includes a small top-off pump. Confirm contents with your specific model.