The Red Sea ReefATO+ is a 3-in-1 system: an auto top off (ATO) that automatically replaces evaporated water to keep your volume and salinity stable, a fully featured digital temperature monitor, and a leak detector — all connected to the ReefBeat app. It ships as standard equipment on every REEFER G3 aquarium.
The Red Sea ReefATO+ Reefer Upgrade Kit is the same 3-in-1 system as the full ReefATO+ — auto top off, temperature monitor and leak detector connected to ReefBeat — in a version Red Sea offers to existing REEFER owners at a lower price.
Our advice
Auto top offs have been around for years in this hobby. Red Sea did not invent the ATO — they took the concept, put their engineers on it, and genuinely improved it: titanium probes with no moving parts instead of a float, a calibrated thermometer and a leak detector built into the same device, with alerts on your phone. We run it on our own systems at the store — the video above is us installing it.
What Red Sea improved
- Solid-state titanium probe level sensor (multi-input EC technology): no float, no moving part to stick or foul.
- Backup pump-off probes placed 2.5 cm (1") above the normal probe: if the level rises too far, the fill still shuts down.
- Fail-safe shutdown if the pump runs too long, with a ReefBeat notification.
- Built-in digital thermometer pre-calibrated to 0.1°: full log plus high and low temperature alerts.
- REEF-SPEC titanium probe leak detector for RO and seawater, with an optional audible alarm.
- 28-day ReefBeat history: hourly fills, volume added, and minimum, maximum and average temperatures.
Specifications (manufacturer data)
- Level sensor: slim-line, multi-input titanium probes, EC technology, with a built-in digital thermometer accurate to 0.1°
- ATO pump: variable flow, serviceable, 6–10 W, 4.5 cm (1.8") diameter — described by Red Sea as quiet
- Max flow: 300 lph (75 gph) — max head: 2.5 m (8')
- Leak detector: REEF-SPEC titanium probes for RO and seawater, ReefBeat notifications with optional audible alarm
- Alerts: temperature out of range, leak detected, reservoir run dry
- Manufacturer warranty: 2 years
What's in the kit
- Water level and temperature sensor
- 12 V DC ATO pump
- Smart ReefBeat controller
- Leak detector
- Magnetic sensor mount for glass up to 12 mm
- 3 m silicone tube with tube holder
- Syphon breaker
- Power supply
Saltwater aquariums only
Red Sea states that the ReefATO+ EC probes require the electrical conductivity that is typical of seawater. This system is not suitable for freshwater aquariums.
Complete your setup
- ReefATO+ Reefer Upgrade Kit — already own a REEFER? Red Sea offers the same system without the magnetic bracket, at a lower price.
- Red Sea ReefCan 18 & 40 — the vertical reservoir built to hold the ReefATO+ syphon breaker and slide into your cabinet.
- ReefATO+ replacement sensor — genuine part R35622 if your sensor ever needs replacing.
- Red Sea ATO float valve — to automatically shut off the RO fill of your reservoir.
Why buy your ReefATO+ at ReefSolution
We are an authorized Red Sea dealer. Our team in Laval runs the ReefATO+ on its own systems and can walk you through installation and ReefBeat setup. Shipping across Canada.
Frequently asked questions
Does the ReefATO+ work in freshwater?
No. Red Sea states the sensor requires the electrical conductivity of seawater: the ReefATO+ is designed for saltwater aquariums only.
What does the ReefATO+ monitor besides the water level?
Two more aquarium health indicators: temperature (digital thermometer pre-calibrated to 0.1°, with a full log and alerts) and leaks (external titanium probe detector). Everything runs through the ReefBeat app.
Which water reservoir should I use with the ReefATO+?
Any RO water container can work, but the ReefCan was designed specifically for it: it holds the syphon breaker and slides vertically into the cabinet.
How it differs from the full system
Red Sea describes it as a drop-in replacement for the stock gravity-fed float valve system of the REEFER: the sensor installs right where your float valve used to sit, in the bracket already built into the sump. That is why the kit does not include the magnetic mounting bracket of the full system — your REEFER simply doesn't need it. Everything else is there.