Marine Monitor (pH/Salinity/Temperature) - Hanna Instruments

The Hanna Instruments Marine Monitor is a purpose-built three-parameter instrument for saltwater aquariums, delivering continuous readings of pH, salinity, and temperature from a single wall-mounted unit. For reef keepers and fish-only system owners alike, having all three parameters on one display—updated in real time—removes the need to juggle separate handheld meters or log-in to a controller app just to verify baseline conditions. The large backlit LCD keeps readings legible at a glance, and the IP65 housing tolerates the humid, salt-laden air typical of a tank cabinet or fish room.

The pH measurement comes from the included HI1286 double-junction, gel-filled electrode. The double-junction design reduces the rate of reference junction clogging that affects single-junction probes in saltwater, resulting in faster stabilization and longer electrode service life. The PEI resin body is resistant to chemical attack and straightforward to clean. Salinity and temperature are handled by a fixed two-electrode conductivity probe with an integrated temperature sensor, which also provides the temperature compensation signal used for accurate conductivity-to-salinity conversion. Both probes ship with 2-meter cables and mount in the tank via the included suction cup clips.

Calibration requires no special equipment beyond what is in the box. pH can be calibrated at one or two points using the included 7.01 and 10.01 pH buffer sachets; salinity calibration is a single-point automatic process using the included 35.00 ppt standard. Electrode cleaning solution is also included. The alarm system allows independent high and low thresholds for each of the three parameters, with the audio alarm configurable if silent operation is preferred.

This monitor is best suited to hobbyists who want reliable, at-a-glance parameter tracking without the complexity or cost of a full aquarium controller. It is a monitoring device only—it does not control dosers, heaters, or other equipment. Mounting hardware for the display (adhesive strips included; screws not included) and 2-meter probe cables give reasonable flexibility for positioning relative to the tank, but users with large sumps or equipment rooms should measure cable reach before purchasing. The 12V DC adapter included is compatible with 115–230V AC mains, making it suitable for international use.