Swimming pool photometers

Pool Photometers: Accurate and Professional Water Quality Control

Swimming pool photometers are devices that accurately measure the chemical parameters essential to keep water safe and healthy. Using optical technology, these devices provide fast and accurate results, facilitating regular water monitoring in a simple and efficient way.

why choose photometers for your pool?

Opting for photometers offers a number of important advantages:

• Accuracy: They provide accurate measurements of critical parameters such as free chlorine, total chlorine, pH, alkalinity and isocyanuric acid.
• Speed and ease of use: They perform rapid analyses in a few minutes, greatly simplifying the water monitoring process.
• Savings: By allowing accurate measurements, they optimize the use of chemical products, avoiding waste and unnecessary expenses.
• Improved maintenance: They facilitate periodic monitoring, helping to prevent problems and maintain constant water quality.

how do pool photometers work?

Photometers use a method called photometry, which measures the intensity of light absorbed by a water sample after the addition of a specific chemical reagent. Depending on the parameter analyzed, the sample changes color in proportion to the chemical concentration present. The photometer measures this color intensity and converts the result into a precise numerical value clearly shown on its display.

Main features of swimming pool photometers

Types of photometers available:

• Portable photometers: Lightweight and handy, ideal for quick testing in any location.
• Benchtop photometers: Designed for intensive use, with capabilities for multiple simultaneous analyses, ideal in public or professional facilities.

Technological innovations:

• Clear, easy-to-read digital display, facilitating immediate interpretation of results.
• Storage function and historical recording of results for better maintenance follow-up.
• Compatibility with multiple reagents to measure several important parameters simultaneously.

Rugged materials and durability:

Manufactured in robust materials, resistant to water and chemicals, guaranteeing a long service life even in demanding environments.

UNE-ISO 17381 Standard: Requirements for Water Analysis Equipment

The UNE-ISO 17381 standard establishes the minimum performance requirements for water analysis equipment, including photometers. This standard ensures that equipment meets quality and accuracy standards suitable for water monitoring in industrial and recreational environments.

Key aspects of standard 17381:

• Accuracy and precision: Photometers must offer a minimum level of uncertainty in their measurements.
• Calibration and validation: The use of standards traceable to internationally recognized bodies, such as NIST, is recommended.
• Environmental conditions: Temperature and humidity ranges are established in which the equipment must operate without affecting their results.
• Maintenance and verification requirements: Procedures are stipulated for cleaning, storage and calibration of photometers to ensure their long-term reliability.
• Compatibility with reagents: The reagents used must meet specific stability and chemical reactivity criteria.

Many modern photometers from brands such as Hanna Instruments, Lovibond and Palintest (Astralpool) meet these standards, ensuring reliable and accurate measurements in swimming pool water analysis and other applications.

Buying Guide: Which photometer is best for you?

Depending on the type of pool and specific needs, here are our recommendations:

• Residential pools and private pools for public use medium size:(Small communities, rural houses, small hotels)
• Large private pools for public use: Sports centers, resorts, tourist complexes.
• Drinking water sector
  • Small facilities : bars, restaurants, canteens
  • Large facilities: Residences, hospitals,

The most important parameters to be analyzed in swimming pool water include:

• Free chlorine: This is the active disinfectant in the water. Ideal range: 0.5-2 ppm (according to RD742).
• Total chlorine: Includes free and combined chlorine. It is recommended that combined chlorine should not exceed 0.6 ppm.
• pH: Affects chlorine efficacy and bather comfort. Ideal range: 7.2-8.0 (according to RD742).
• Alkalinity: Helps stabilize pH. Ideal range: 80-140 ppm.
• Calcium hardness: Prevents corrosion and staining. Ideal range: 200-400 ppm.
• Cyanuric acid: Stabilizer that protects chlorine from UV light. Ideal range: 25-30 ppm, with a recommended maximum of 75 ppm.
• Bromine: Alternative to chlorine in some pools. Ideal range: 2-5 ppm.
• Turbidity: Indicator of filtrate quality. Maximum allowable value 5 NTU, although some local regulations require less than 2 NTU.

Photometry and measurement principles

Photometry is based on the absorption of light by chemicals in solution. The Beer-Lambert equation defines the relationship between light absorption and the concentration of the analyte in the sample. Advanced photometers use this principle to provide accurate and reliable results.

To avoid errors in measurements of chlorine, pH and other parameters, it is important to consider:

• Reagents in poor condition: avoid using expired reagents or reagents from mixed batches.
• Incorrect filling of cuvettes: Use a syringe to avoid bubbles.
• Incorrect reaction time: Wait the appropriate time (e.g. 1 min for free chlorine, 2:30 min for total chlorine).
• Measurement in dirty equipment: Regular cleaning of cuvettes with suitable cloths.
• Incorrect use of standards: Check with NIST-traceable standards at least once a month.

Key technical concepts explained

• Photometry: Analytical technique that measures the absorption of light by chemicals in liquid samples to determine their exact concentration, based on the Beer-Lambert equation.
• Chemical reagents: Specific substances used to cause a reaction detectable by the photometer, facilitating precise measurement of the parameter under analysis.
• Essential chemical parameters: Free chlorine, total chlorine, pH, alkalinity, calcium hardness, cyanuric acid and bromine, essential for maintaining water quality.
• Influence of pH on disinfection: A pH closer to 7.2 maximizes the effectiveness of free chlorine, while values above 7.6 reduce its disinfectant capacity significantly.
• Combined chlorine and chloramines: It is formed when chlorine reacts with organic compounds, reducing the disinfectant capacity and generating unpleasant odors. Its concentration should not exceed 0.6 ppm.
• Water turbidity: Measured in NTU, it indicates the amount of suspended particles and affects the effectiveness of disinfection. The maximum allowable value is 5 NTU, although some local regulations require less than 2 NTU.
• Equipment correction and calibration: Use of NIST-traceable standards to verify the accuracy of photometers at least once a month, avoiding errors in the measurement of water parameters.