Free and Total Chlorine, pH, Alkalinity, and Cyanuric Acid are some of the most important parameters when maintaining a safe and clean pool.
Chlorine is a common chemical used by many due to is disinfection properties. Free chlorine can exist in two forms and which form is present is based on the pH. At pH less than 7.6 hypochlorous acid (HOCl) is the predominate form found while at pH greater than 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. Total chlorine represents both the free chlorine and combined chlorine present. Combined chlorine is the chlorine bound to nitrogen substances such as ammonia. In swimming pools, combined chlorine that we can smell, is irritating to the eyes. A free chlorine measurement is subtracted from a total chlorine measurement to determine how much combined chlorine is present.
Alkalinity is also a very important parameter in monitoring swimming pool water chemistry. Alkalinity is the buffering capacity of a solution to resist change from an acid or base. Chlorine can also be a base that will increase the pH of the water as it is added to it. Having a sufficient level of alkalinity helps to buffer against the pH so that it takes more over time in order to cause a pH change.
Cyanuric acid is often added to a swimming pool to prevent the loss of chlorine to sunlight. Cyanuric acid is commonly found in dry chlorine such as trichloroisocyanurate (trichlor). This form can be purchased as a solid “puck” and placed in flotation devices to erode slowly into the water. Maintaining the proper level of cyanuric acid will increase the life of chlorine in the pool. Cyanuric acid will build up overtime as more chemical is added. Unfortunately, having too much will decease the Redox (ORP) potential that is effective at killing the bacteria in the pool. For this reason cyanuric acid should be measured for pools that are using it as a stabilizer.
Important Note: Chlorine by DPD chemical measurement is preferred over ORP measurements due to the masking of the oxidation potential from chlorine and other oxidizers when using cyanuric acid (isocyanurate containing sanitizers) as a stabilizer. It will be possible to obtain a 625 -650 mV ORP reading when using cyanuric acid.
HI971044 allows any user to measure these key swimming pool water quality parameters with laboratory grade accuracy. The reagents are pre-made and the meter offers a tutorial mode to guide the user step by step in performing the measurements.
The HI971044 has an innovative optical system that offers superior performance in accuracy, repeatability, and the short amount of time it takes to perform a measurement. This compact, waterproof meter is extremely user friendly with a tutorial mode that walks the user graphically, step by step, in performing a measurement. The use of a backlit dot matrix LED allows the use of virtual keys which makes the operation of the meter very intuitive including selecting different units of measure, reviewing GLP data, recalling the last 50 measurements, and customizing the meter to user preferences.
HI971044 is completely waterproof including the cuvette holder that is designed with ridges to protect the optical path from getting scratched by the cuvette and a gasketed battery compartment that holds three common AA batteries. The compact design fits comfortable in the hand for use in the field or on a table for benchtop use. The LCD is 71 mm (2.75″) by 37 mm (1.6″) and is backlit for easy viewing under all conditions.
- LED that generates very little heat
- 8 nm narrowband interference filter that is accurate to +/- 1 nm and offers 25% increase in light efficiency.
- Reference detector that modulates the voltage to LED for consistent light output.
- A concave focusing lens that reduces errors from imperfections in the cuvette
Advanced features including CAL-Check to verify performance, GLP for last calibration date, setup options, and the ability to see all accessories used with the meter.
When enabled, the tutorial mode will guide the user step by step through the measurement process .
Choice of powder or economical liquid reagents for chlorin measurments.
Stable Light Source:
- The internal reference system of the HI9771044 photometer compensates for any drifts due to power fluctuations or ambient temperature changes. With a stable source of light the readings are fast and stable between your blank (zero) measurement and sample measurement.
High Efficiency Light Source:
- LED light sources offer superior performance compared to tungsten lamps. LEDs have a much higher luminous efficiency, providing more light while using less power. They also produce little heat, which could otherwise affect electronic stability.
High Quality Filters:
- Improved optical filters ensure greater wavelength accuracy and allow a brighter, stronger signal to be received. The end result is higher measurement stability and less wavelength error.
Greater Light Yield:
A focusing lens collects all of the light that exits the cuvette, eliminating errors from imperfections and scratches that may be present in the glass. The use of the convex lens reduces the need for indexing cuvettes.
CAL Check Functionality:
- Hanna’s exclusive CAL Check feature allows for performance verification and calibration of the meter using NIST traceable standards. Our CAL Check standard vials are developed to simulate a specific absorbance value at each wavelength to verify the accuracy of subsequent readings.
Built-in Reaction Timer:
Waiting the proper reaction time is of key importance when performing colorimetric measurements. The countdown timer displays the time remaining until a measurement will be taken, ensuring consistent results between sample measurements and users.
Large Cuvette Size:
- The sample cell of the HI971044 fits a round, glass cuvette with a 25 mm path length. The relatively long path length of the sample cuvette allows the light to pass through more of the sample solution, ensuring accurate measurements even in low absorbance samples.
Intuitive Dot Matrix Display:
- The HI971044 is designed with a backlit, graphic LCD. With virtual keys, a battery status indicator, and error messages. Users will find the meter interface intuitive and easy to read. A dedicated help key provides information relating to the current meter operation, and can be used at any stage in the setup or measurement process to show contextual help.
The meter uses three common AA batteries that allow for about 800 measurements to be taken. The auto-off feature automatically shuts off the meter after 15 minutes of inactivity in order conserve battery life.