Milwaukee pH Probe - Hydros

The Milwaukee MA911 pH probe is a reliable, gel-filled sensor built for continuous use with Hydros controllers and compatible monitoring equipment. Gel-filled probes maintain a stable internal reference solution without the mess or maintenance concerns associated with liquid-filled designs, making them a practical choice for reef and marine aquarium applications where consistent pH monitoring is critical.

The probe uses a double-junction construction, which places a secondary barrier between the internal reference electrolyte and the sample water. This significantly reduces the likelihood of clogging at the junction — a common failure point in single-junction probes, particularly in high-salinity or organically rich water. The spherical glass sensing tip increases the active surface area in contact with the water, which translates to faster response times and more stable readings.

The resin body is built to handle the physical realities of an active fish room. It resists cracking from accidental drops or bumps and shields the fragile glass bulb from damage during handling. The included 6.6-foot cable gives hobbyists flexibility in positioning — long enough to route from a sump to a controller mounted on a wall or equipment rack without excessive strain on the connector.

This probe is a direct fit for Hydros-ecosystem users looking for a replacement or spare sensor. As with all pH probes, periodic calibration using fresh two-point calibration solution is essential to maintaining measurement accuracy. Storage in pH 4 or 7 calibration solution when not in use will extend the probe's service life.