Pool water – importance of pH – ORP balance

Category: Pools | Tags:
Whether you are
a hotel pool manager,
swimming pool or hot tub owner,
we have a solution for the cleanliness
and sanitation of your pool water.
The efficacy of sanitizers, concentration or ORP is highly dependent on a controlled pH value.
Technology and proper maintenance can keep your spa water fresh and clean.
The most commonly used means for sanitation and treatment of pool water is chlorine because of it’s strong oxidizing properties: it kills bacteria, viruses, other microorganisms, as well as other contaminants very successfully.
It can seem simple, you have water, add chlorine, but how to keep it in balance?
If we talk about oxidation in pool water, most important parameter is ORP: oxidation-reduction potential.
It tells us how effective chlorine or some other oxidizers are in the water.
For measuring ORP we use ORP probes that detects voltage between electrodes and gives us a value whose unit of measurement is milivolts (mV). Oxidizers will show positive mV charge, while contaminants will show negative mV charge. Various ORP controllers or testers can help us in determining the quantity of an oxidizer that is beeing used for sanitation of water. Although optimal concentration levels vary depending on the type of cleaning agent, the ORP level should be maintained between 700 mV and 750 mV for pools and spas.
With chlorine disinfection there is an inverse relationship between pH and ORP. As the pH level increases, the ORP level decreases.
Why pH is important?
The goal is balancing values between 7.2 and 7.6 pH
Free chlorine can exist in two forms and which form is present is based on the pH.
pH < 7.6 the predominate form is hypochlorous acid (HOCl)
pH > 7.6 the hypochlorite (OCl–) form becomes predominate
This is very important when it comes to preventing biological growth in water or keeping a swimming pool safe since hypochlorous acid is 100 times more effective as a sanitizer. Changes in pH value will affect the HOCl equilibrium in relation to the hydrogen and hypochlorite ions.
To prevent pH from drifting and minimize changes in pH, most important is to keep Alkalinity between 80-150ppm.
There is a variety of HANNA efficient water treatment systems available which can give very positive results together with proper maintenance. To measure pH and ORP value, Hanna Instruments have various devices that can help you in sanitation of pool water. From automated process controllers, to simple hand testers, ensure carefree swimming and pool fun with Hanna Instruments.

BL122 • BL123

pH/ORP Controllers
with Cloud Connectivity
With chlorine disinfection there is an inverse relationship between pH and ORP. As the pH level increases, the ORP level decreases.
The BL120 utilizes a dosing consent feature that will not dose chlorine until the pH value is first corrected since it is possible to have a low ORP value even though there is sufficient chlorine. The dosing consent feature prevents wastage of chemicals and avoids a higher than necessary chlorine concentration.
BL122 and BL123 are designed to maintain constant pH and ORP (disinfectant levels) in swimming pools, hot tubs, and spas and offer the added benefit of allowing remote connection and access to devices via the Hanna Cloud web app. These controllers are available in two configurations. The basic version is the inline model which allows for direct installation of probe and chemical injection fittings into existing piping. A panel mounted version with a bypass fl ow cell is also available. The bypass flow cell allows for calibration and maintenance of the probe without having to shut down the recirculation pump.
Hanna Cloud is a web-based application that connects you to measurement devices such as the BL122 and BL123. Measurements and data storage are accessible from your PC, tablet or phone. Measurements, trends, history, device settings, alarms, and messages are transmitted to your “Dashboard” as your instrument measures and controls your process.

BL120 • BL121

pH/ORP Controllers
with Built-In Chemical Feed Pumps
These Swimming Pool Controllers are a complete system designed for maintaining swimming pool, hot tub, and spa disinfection water quality. These controllers are available in two configurations. The basic version is the in-line model which allows for direct installation of probe and chemical injection fittings into existing piping. A panel mounted version with a bypass flow cell is also available. The bypass flow cell allows for calibration and maintenance of the probe without having to shut down the recirculation pump.

BL101

Pool Line ORP Controller
and Dosing Pump
Engineered to be an inexpensive solution for homeowner and maintenance companies to maintain the ideal ORP at all times of a swimming pool or hot tub. The BL101 Pool Line ORP Controller and Dosing Pump is a complete solution with both a process controller and a chemical dosing pump. Simply insert the probe and injection valve in-line with the re-circulation pump and supply the oxidizer (i.e. chlorine) to be dosed.
  • All in one solution for maintaining the proper ORP value
  • Industrial process probe with 1/2 NPT threads for insertion into re-circulation line
  • Input for level controller or flow switch
Direct pH and ORP measurements in the pool!

HI981954

Multiparameter
Waterproof Meter
HI981954 Pool Line Multiparameter Waterproof Portable pH/ORP/EC/Temperature meter is made for measuring key water quality parameters in swimming pool, hot tub, or spa water.
This is an advanced meter uses a single weighted probe with multiple sensors to measure multiple parameters simultaneously and display results as pH, pH in mV, ORP, conductivity (EC), total dissolved solids (TDS), salinity, and temperature.
The meter has a built-in pressure transducer for barometric pressure readings.
  • One probe with field replaceable pH/ORP, EC and temperature sensors
  • Auto-ranging for EC and TDS readings
  • Display up to 11 measurements simultaneously

HI981914

Professional Waterproof
Portable pH/ORP/ISE Meter
HI981914​ Pool Line professional waterproof portable pH/ORP meter is made for measuring pH and ORP of a swimming pool, hot tub, or spa water. This is an advanced meter with many features including Hanna’s exclusive CAL Check pH electrode diagnostics that is used to identify potential problems including when to clean the electrode, check a buffer for contamination and the overall health of a pH electrode. This function can be used to identify issues with process probes that have a BNC connector.
  • Laboratory grade measurements in a portable
  • CAL Check advanced probe diagnostics
  • Troubleshooting tool for the maintenance of process probes

HI991003

Waterproof Portable pH/pH-mV/ORP/
Temperature Meter with Sensor Check™
The HI991003 is a compact, waterproof, portable pH/pH-mV/ORP/temperature meter that is supplied complete including a rugged carrying case and a unique titanium body pH/ORP electrode that has a built-in temperature sensor. This meter comes with our unique Sensor Check™ feature that allows the user to determine the electrode status at any time. The meter features a large, dual level LCD display for easy viewing of the pH, pH-mV, ORP, temperature, and status indicators. The operation of the meter is simplified to two buttons. The HI991003 has an exceptional long battery life of 1400 hours of continuous use.
  • Automatic Temperature Compensation
  • Automatic Two-Point Calibration
  • Waterproof
Spot checking of smaller pools can be made fast and accurately with handheld testers.

HI981214

pH/ORP/Temperature
Pool Line Combo Tester
pH/ORP meter is made for measuring pH and ORP of a swimming pool, hot tub, or spa water. This lightweight, waterproof tester offers high accuracy pH, ORP, and temperature measurements in a single handheld unit. No more switching between meters for your routine measurements.
  • Waterproof
  • Replaceable pH electrode
  • Automatic calibration
Author: Nives Vinceković Budor
mag.ing.chem.ing
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