The Hanna Instruments BL12x swimming pool controllers are automatic systems, specially designed to measure and control pH and free-chlorine levels. The chlorine level is measured based on the ORP or REDOX principle.  An increase in the ORP value correlates with an increase in the free-chlorine level.

pH and ORP testing are done together for efficient disinfection and control. The efficacy of sanitizers, such as chlorine, depends on a controlled pH value.  The ORP value is the most consistent indicator of the sanitizing effectivness of the pool or spa.  Typically 650 -750 mV at 7.2 pH indicates proper water treatment.

The BL122 & BL123 offer the added benefit of allowing remote access and visualizing of measured date via Cloud connectivity. All measurements and main events are sent to Hanna Cloud through the Ethernet connection.

Keep Track Anywhere with Hanna Cloud Connectivity (BL122 & BL123)

Hanna Cloud is a web-based application that connects you to the BL122 & BL123. Measurement and data storage are accessible from your PC, Tablet or Phone. Multiple devices can be registered to a single Hanna Cloud Account.

For BL121 & BL123 three analog outputs are available that allow connection to an external chart recorder or datalogger to monitor any of the three measured parametrs. The outputs are scalable, offering increased flexibility and better resolution as needed.

Any of the controllers can be paired with the HI1036-18xx digital probe. The probe incorporates pH, ORP and temperature sensors along with a matching pin. It was specially designed to detect a broken electrode based on a shifted zero potential value, around 4 pH.

The HI1036-18xx uses an Ag/AgCl reference with 3.5 M KCL. The ORP values are referenced to it. Measurement data stored on the probe is transferred to the controller via digital connection; thus eliminating noise and static due to high impedance signals carried by the cable.

Swimming Pool Controllers are available in two configurations – BL12x:

  1. In-line, for direct probe installation and chemical injection fittings into existing piping
  2. Flow Cell, for calibration and probe maintenance without having to shut down the recirculation pump

Main Features:

  • Two (2) built-in peristaltic dosing pumps with proportional control
  • Multicolored LED Indicators
  • Adjustable Flow Rate
  • ORP (Chlorine) Dosing Consent
  • Acid & Chlorine Tank Level Inputs
  • Programmable Alarm System
  • Automatic Logging
  • GLP (Good Laboratory Practice)
  • Analog Outputs (BL121 and BL123)
  • USB Connectivity (users can easily transfer data to a PC)
  • Ethernet Port for Hanna Cloud Connectivity (BL122 & BL123 only)
  • Password Protected


Renee Christoph
Hanna Instruments
Durban Tel. +27 31 701 2711
Johannesburg (head office) Tel. +27 11 615 6076
Eastern Cape Tel. +27 41 450 5685
Cape Town Tel. +27 21 946 1722
Export Division Tel. +27 72 910 5749


Share this article