The secret to make fountains work and last: the automatic pH/Redox control

Capiamo assieme perché un dosatore a lambimento non potrà mai sostituire un pannello di controllo e dosaggio automatico pH/Redox
The secret to make fountains work and last: the automatic pH/Redox control

Let’s understand together why a lapping chlorinator can never replace an automatic pH/Redox control panel


A clean, crystalline and without limestone water is the main element in a fountain. The chemical control of the water is the fundamental element to ensure the life and durability of a fountain over time. A project can be compromises by cloudy or greenish water, both from an aesthetic and sanitary point of view; but the worst thing for the functioning of the fountain is the lack of management of the limestone, which leads to irreparable damage in a few months, making last the fountain even less than the warranty.

More and more often we are asked to intervene with renovations or adjustments of young fountains, built a few years ago. In most cases, these are projects that have a lapping chlorinator (also called chlorine doser flush chlorinator), installed in place of the control panel for automatic pH and Redox dosing. It is a cheap solution, both in terms of money and performance, which doses the chlorine tablets through a mechanical regulation of the flow, which does not offer any check on the quantity of product, with consequent overdoses or total absences.

Fountains, and in particular water features, necessarily need filtered water – in order to avoid the proliferation of algae, bacteria and viruses – and a very low limestone content – which clogs the nozzles, covers every structural part making it white/ yellowish, but above all it deforms and blocks pumps, pipes and nozzles until they are unusable. So, in addition to being unsightly, limestone is the number one enemy of fountains.


Designing a fountain, the very first thing to do is the evaluation and calculation of the correct sizing of the filtration system. Only then, we focus on the automatic filling with the three-way sensor, on the overflow and on the water drain. Finally, after completing these steps, we move on to the playful and emotional aspect of the fountains, leaving full freedom to creativity and technological innovations to offer ever new and original water and light effects.


In the sustainable fountains of Forme d’Acqua, mechanical filtration is given by the glass grit filter. Glass, in fact, compared to the sand used in the past, is three times more effective and durable, thus making it possible to postpone maintenance and give a greater guarantee of interventions.

Accordingly to the UNI 10637/2016 swimming pool regulation, the daily water recirculation times vary on average from 3 to 4 hours, depending on the depth and the prevailing activity of the pool. Forme d’Acqua calibrates the recirculation times of its fountains taking into account this legislation. However, sometimes reality must also consider parameters that go beyond the tables relating to depth and use: it happens that fountains have a very low volume of water and an extensive surface in contact with the atmosphere and therefore with pollutants and dust. In this case, a further adjustment must be made, sizing the filter also to the area covered by the water feature.

The UNI 10637/2016 standard is also very specific in chemical filtration, offering values falling within certain ranges, which Forme d’Acqua applies with precision in the design and construction of its fountains, entrusting it to the control panel for automatic pH and Redox dosing. From a technological point of view, this type of panel is very advanced, because it is connected, interrogated and managed remotely; moreover, it is equipped with log. These functions are essential to be able to provide effective and timely assistance to the customer and to intervene in the event of alarms, for example due to product exhaustion. Its use is simple and intuitive:

  • set the correct pH and Redox values;
  • the probes constantly detect the values of the water through the filtration circuit;
  • the control unit reads the values and, if necessary, integrates the liquid acid and chlorine via two dosing pumps, keeping them constantly balanced.

The lack of an automatic panel that constantly detects acid and chlorine levels means that the water is not really clean, favouring the deposit of limescale – up to layers of up to 5mm – which in the medium term damages the MEP parts (mechanical, electrical and plumbing). Furthermore, sulfuric acid has an important function of stabilizing the pH within certain values, which allows sodium hypochlorite (chlorine) to carry out its disinfectant activity (contrary to pH that is too acidic or basic, it decreases).


Unlike the pH and Redox control and automatic dosing panel, the lapping chlorinator (in line or with bypass) is a very basic and imprecise system, that is connected to the fountain’s recirculation system, or directly to the delivery pipes of the fountain’s water, and filled inside with chlorine tablets. The water arrives in the dispenser, mixes with the chlorine and put back into the tank. In this way it is lapped in an indeterminate way, because the quantity of chemical product released into the water varies according to the quantity of product introduced and contained in the box itself. To understand if the chlorine values are correctly balanced, it is necessary to analyse the water manually with special testers (the same ones used for swimming pools) and vary the concentration of the product by manually intervening on the regulating valve. However, chlorine is a strongly oxidizing agent, which leads to the rapid deterioration of the chlorinator itself and of the regulating valve: to solve the problem, sometimes tablets of chlorine are thrown into the fountains, violating the regulations in terms of safety, but also common sense.

cloratore-a-raso-Model-724x1024The lapping chlorinator is an unsuitable system for guaranteeing water quality and safety, because it can lead to an excessive use of chlorine, with the consequent release of its suffocating smell. But also, if we take as an example the flush fountains, which in periods summer become a play area for children, in cases of irritation of the respiratory tract and skin or eyes. Otherwise, a too low quantity of chlorine in the water leads to the proliferation of algae, viruses and bacteria and therefore to its unhealthiness, with risks to the safety of the people who come into contact with it.

Finally, in a sustainable and safe fountain, there must be a filtration system and control panel for automatic pH and Redox dosing designed and built in compliance with current regulations on the subject. An MEP design that does not take into account the possible damage generated by an ineffective control of limestone and chlorine is the reason why we periodically intervene on fountains built by third parties that are less than two years old.

January 30th 2023

Susanna Dei Rossi

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