Automatic Control Panel

Pool Metering Panels: Everything You Need to Know

In a world so automated and with so much technology, control panels are basic tools for pool maintainers and those responsible for aquatic facilities. They ensure that critical water parameters, such as chlorine and pH levels, are maintained at the proper values, providing peace of mind, safety and regulatory compliance.

These systems not only measure but also monitor water chemistry levels, reducing the need for manual intervention and ensuring optimal water quality in private, community, semi-public and water park pools. In addition, many models include WiFi connectivity and remote control, making it easy to monitor from anywhere, anytime.

what do the Control Panels Measure?

The main purpose of a measurement panel is to monitor and automatically adjust the pH and chlorine levels in the water.

• PH Measurement: Its operation is relatively simple. It is based on a sensor that measures the level of acidity or alkalinity of the water. This sensor is connected to an electronic system that regulates the injection of acid or base to maintain the pH within the optimum range (7.2 - 7.6).
• Chlorine measurement in PPM: This is where we find the biggest differences, as there are three main technologies for measuring chlorine in water in PPM.
• ORP-Redox measurement of chlorine: This method measures the oxidation-reduction potential (ORP) of water, indicating its disinfection capacity. Instead of directly measuring the amount of free chlorine, it evaluates the effectiveness of chlorine and other oxidants in removing contaminants. It is expressed in millivolts (mV) and is a practical and economical option for water monitoring in residential and commercial pools.
• Chlorine measurement in PPM: Panels can measure chlorine using different technologies, each with its advantages and specific applications.

a) Amperometric Measurement

• This is one of the most widely used technologies in commercial and residential pools.
• It is based on submerged electrodes that generate an electric current proportional to the concentration of chlorine in the water.
• It requires periodic maintenance, as the electrodes can become dirty or out of calibration.
• It can be affected by the presence of other chemicals in the water, such as stabilizers.

b) Potentiostatic measurement

• A more advanced variant of amperometric, with a more stable control.
• It uses an electrochemical reference system that allows more accurate measurements with less interference.
• Its main advantage is that it offers greater long-term stability and reduces the need for frequent calibrations.
• Its cost is higher compared to basic amperometric systems. c) Photometric measurement This system measures chlorine by an optical process.
• It is based on the absorption of light by chlorine in a water sample.
• It is very accurate and is not affected by other chemicals.
• It is often used in laboratories or in pools that require extremely precise control.
• It is not a continuous real-time measurement system, as it requires a sampling cycle to obtain the data.

which one to choose for your pool?

• The choice of metering panel will depend on the type of pool and the level of accuracy required:
• Residential pools: an amperometric system is usually sufficient.
• Commercial pools or pools with a high volume of bathers: Potentiostatic technology offers greater stability.
• High-standard pools or laboratories: Photometric measurement provides maximum accuracy.
• In addition to the measurement technology, it is important to consider the quality of the sensors, ease of calibration and compatibility with automatic dosing systems.

ORP-Redox chlorine measurement:

The ORP (Oxidation-Reduction Potential) or Redox measurement system is one of the most widely used ways to evaluate the disinfection capacity of water in swimming pools. Its operation is different from technologies that measure the concentration of free chlorine, as it focuses on the oxidative capacity of the water, making it a practical and economical method.

what is ORP or Redox?

Oxidation-reduction potential (ORP or Redox) measures the ability of water to oxidize organic matter and disinfect. In other words, it indicates the effectiveness of chlorine and other disinfectants in eliminating microorganisms and contaminants.

ORP is expressed in millivolts (mV) and its value will depend on factors such as:

• The concentration of chlorine in the water.
• The pH of the water (high pH values reduce the effectiveness of chlorine).
• The presence of contaminants and stabilizing compounds, such as isocyanuric acid. How does an ORP sensor work? The ORP measurement system uses a sensor submerged in the water that measures the electrical potential difference between a reference and the pool water.
• If the ORP is high (>750 mV), the water has good sanitizing power.
• If the ORP is low (

In general, an ORP of 650-750 mV is considered optimal for a well sanitized pool.

Advantages of the ORP System

• Inexpensive: It is more affordable than other free chlorine measurement systems.
• Easy installation and maintenance: Only requires occasional sensor calibration.
• Allows real-time control: Provides continuous measurement of the disinfecting power of the water.
• Compatible with automatic dosing systems: Can be integrated with dosing pumps to adjust the amount of chlorine injected.

Limitations of the ORP System

• Does not directly measure the amount of free chlorine: It only evaluates the oxidizing capacity of the water, which can be affected by other chemicals present.
• Sensitivity to pH: High pH reduces the effectiveness of chlorine and can alter ORP readings.
• Influence of stabilizers and contaminants: The presence of isocyanuric acid or other compounds can affect the measurement.

when to Choose an ORP System for your Pool?

• Residential pools: It is a practical and affordable option for basic sanitizer control.
• Public or commercial pools: Can be used in combination with other free chlorine measurement systems to improve accuracy.
• Automated systems: Ideal for automatically adjusting chlorine dosing in pools with pH and ORP controllers.

Comparison between Chlorine Measurement Systems: PPM vs. ORP

Both systems have advantages and disadvantages depending on the type of pool and the level of accuracy desired. Below, we will explain each and offer a final comparison.

1. PPM Chlorine Measurement

The PPM measurement system is based on the actual concentration of free chlorine present in the water. This method allows to know how many chlorine particles are dissolved per million parts of water.

Advantages of PPM measurement:

• Accurate measurement of free chlorine concentration.
• It is not affected by variations in pH or the presence of other chemicals.
• It is the recommended method for complying with public health regulations in commercial and municipal pools.

Disadvantages of PPM measurement:

• It does not measure the effectiveness of chlorine in disinfection, only its quantity.
• There may be presence of combined chlorine (chloramines), which does not disinfect effectively but still appears in the measurement.
• Requires frequent calibration in electronic systems to maintain accuracy.

2. ORP Chlorine Measurement (ORP or Oxidation-Reduction Potential)

The ORP system measures the ability of water to oxidize and remove organic matter. Instead of indicating the exact amount of free chlorine, it provides a value in millivolts (mV) that reflects the disinfection activity of the water.

Advantages of ORP measurement:

• Measures the actual disinfection capacity of the water, not just the amount of chlorine.
• It allows real-time control by means of automated systems.
• It is an economical system and easy to install in residential pools.

Disadvantages of ORP measurement:

• Values can be affected by pH and other chemicals in the water.
• Does not give an accurate measurement of the amount of free chlorine in PPM.
• Can be confusing if not interpreted correctly, as high ORP does not always mean there is enough chlorine in the water.

Choosing the Metering Pump in a Pool Control Panel

Once we have defined the type of control panel we will use for chlorine measurement (ORP or PPM) and, in the case of PPM, the specific method of measurement (amperometric, potentiostatic or photometric), the next step is to choose the appropriate metering pump.

The dosing pump is the mechanical component responsible for injecting the chemical into the water in a controlled manner. Its activation or deactivation depends on the commands sent by the control panel, thus ensuring that the chlorine and pH levels are maintained within the optimal parameters.

1. Function of the Dosing Pump in the Control Panel

The dosing pumps work in conjunction with the control panel and are responsible for:

• Inject sodium hypochlorite (liquid chlorine) when a decrease in chlorine level is detected.
• Inject pH reducer or pH increaser when the pH sensor detects a variation outside the recommended range (7.2 - 7.6).

2. Types of Control Panel Settings

Depending on the level of sophistication of the system, control panels can have two main configurations in relation to the dosing pump:

A) Control Panel with Independent Control Unit and External Pumps

• In this system, the control unit is separate from the metering pumps.
• The control unit measures and sends signals to the pumps to activate or deactivate dosing.
• Typically, this type of configuration is found in advanced panels, ideal for commercial pools or installations with high water treatment requirements.

Advantages:

• Greater flexibility, since it allows to choose and change pumps according to the need.
• Possibility of using pumps of different capacities according to the size of the pool.
• Greater durability and ease of maintenance.

Disadvantages:

• Requires more space for installation.
• Higher initial cost, since the components are purchased separately.

B) Control Panel with Integrated Metering Pumps

In this case, the control panel already incorporates the dosing pumps within its structure. The whole system is integrated into a single unit, where metering and dosing are performed from the same unit.

They are most commonly found in simple and compact panels, designed for residential or smaller pools.

As a general rule the measurement technology is limited to ORP-Redox

Advantages:

• Easier and more compact installation.
• Ideal for small spaces.
• Lower initial cost compared to advanced systems.

Disadvantages:

• If a pump fails, repair or replacement may be more complicated.
• Less flexibility in the choice of individual components.

3. Types of Metering Pumps

Within the control panels, we can find different types of metering pumps according to their operating mechanism:

A) Peristaltic Pumps

They work by means of a flexible tube that is compressed by a rotor to inject the chemical product.

They are ideal for small and medium-sized pools.

Advantages:

• Low maintenance and easy replacement of the tubing.
• Accurate and economical.
• Quiet operation.

Disadvantages:

• Not suitable for large volumes of water.
• Tubing wears out over time and requires replacement.

B) Electromagnetic Pumps (Solenoids)

They work by means of an electromagnetic piston that pushes the chemical product under pressure. They are used in commercial pools or in systems that require more precise dosing.

Advantages:

• Higher dosing accuracy.
• Suitable for more demanding applications.
• Rugged and long life.

Disadvantages:

• They are more expensive.
• They are noisier than peristaltic pumps

4. how to Choose the Right Metering Pump?

To select the right metering pump within a pool control system, the following factors should be considered:

• Pool size: Larger pools require pumps with greater dosing capacity.
• Type of control panel: If the panel already integrates pumps, no external selection is required.
• Type of chemical to be dosed: Liquid chlorine, pH reducer or pH increaser.
• Frequency of use: In commercial pools, a system with electromagnetic or piston pumps is recommended, while in residential pools, peristaltic pumps are usually sufficient.
• Ease of maintenance: Peristaltic pumps are easier to maintain than electromagnetic pumps.

Regulations at España

Metering and control panels in swimming pools must comply with the regulations in force in España, especially in public or community pools.

Some of the most relevant regulations include:

• Royal Decree 742/2013, which establishes the technical-sanitary criteria for swimming pools. This decree regulates the minimum and maximum levels of parameters such as pH, free residual chlorine, chloramines and ORP, among others.
• Standard UNE-ISO 17943, related to the measurement and control of chemical substances in swimming pool water.

Regulation of the quality of water for human consumption, which can influence the treatments applied in swimming pools. It is essential that the measurement panels are able to ensure compliance with these regulations to avoid penalties and ensure the safety of bathers.