The AC Infinity AI Hydro Sensor is an in-tank probe for the Controller AI+ that reads pH, EC, TDS, salinity and water temperature continuously and logs the lot to the app. It replaces the routine of dipping a pen twice a day with a live line on a chart — and because the controller can act on what it reads, it turns dosing and top-ups into something the system handles rather than something you remember to do.
Continuous numbers instead of snapshots
A pen reading tells you what the tank was doing at the moment you dipped it. Most of the interesting movement happens in between — pH drifting overnight, EC climbing as the plants take water faster than nutrient, temperature rising through the afternoon. The hydro sensor sits in the reservoir and logs all of it, so you see the shape of the day rather than two dots on it.
That history is the practical value even before any automation. It shows you whether your pH drift is a buffering problem or a feeding problem, whether your EC rise is evaporation or uptake, and how warm your tank actually gets when the lights are on.
Let the controller act on it
Paired with the Controller AI+, the readings become triggers. Peristaltic dosing pumps can run to a pH or EC target, water pumps can top up against a value, and anything on a UIS Control Plug — a chiller, an air pump, a circulation pump — can be switched on the same data. Alerts push to your phone when a number goes out of range, which is the part that saves a crop when something fails while you are out.
Replaceable probes, included calibration
pH probes are consumables — they drift and eventually die, in every system from every manufacturer. This one is built with interchangeable probes, so a worn element is a part swap rather than a new sensor. Six calibration solutions come in the box: pH 4.00, 7.00 and 10.01, plus 12.88 mS/cm, 1413 µS/cm and 84 µS/cm for EC. Calibrate on arrival and then on a routine, the same as you would with a hand pen.
Specifications
| Product identification | |
| Manufacturer | AC Infinity Inc. |
| Product name | Hydro Sensor for Controller AI+ |
| Model | AC-HDS3 |
| UPC | 819137024885 |
| Dimensions | |
| Sensor dimensions | 5.3 × 5.3 cm (2.08 × 2.08 in) |
| Cord length | 3.66 m (12 ft) |
| Performance and technical | |
| Detection | pH, EC, TDS, salinity, temperature |
| Probes | Interchangeable / replaceable |
| Water resistance | IP68 |
| Power | 3.6 V |
| Included calibration solutions | pH 4.00, pH 7.00, pH 10.01, 12.88 mS/cm, 1413 µS/cm, 84 µS/cm |
| Compatibility | Controller AI+ (AI sensor port) |
| Warranty | 2 years on the sensor unit. Probes and calibration solutions are consumables with shorter cover. |
| Documentation | |
| Quick start guide | |
| Calibration guide | AC Infinity hydro sensor calibration guide |
FAQ
What controller does it need?
The Controller AI+ — it plugs into an AI sensor port, which the Controller 69 Pro and Pro+ do not have.
Does it dose the nutrients by itself?
It provides the readings and the triggers; the dosing hardware is separate. Peristaltic pumps or solenoids run from the controller — through a UIS Control Plug for outlet-powered units — and the sensor is what tells them when. Tell us what pumps you are running and we will confirm the arrangement before you order.
How often does it need calibrating?
Treat it like any pH instrument: calibrate on setup, then on a regular routine and any time a reading looks implausible. The six solutions in the box cover the standard pH and EC points, so you are not buying anything extra to get started.
Can I use it in an aquarium or a pool?
Yes — it is an IP68 water-quality probe and the readings are the same ones those applications care about. The automation side is where it gets interesting: a chiller, air pump or dosing pump on a control plug responds to the same data.
What happens when the pH probe wears out?
You replace that probe rather than the whole sensor. All pH electrodes are consumables with a working life, so this is normal maintenance rather than a fault — the replaceable design is there because AC Infinity expect it. That is also why the probes and calibration fluids carry shorter warranty cover than the 2 years on the sensor unit.
Where in the tank should it sit?
In moving water, well below the surface and away from the return where fresh nutrient or pH adjuster enters. A probe sitting in a dead corner reads that corner; one sitting under the dosing line reads the dose.