Swimming pool with drinking water specifications

If the size, the shape, the surface coatings, the surrounding area of ​​a pool are elements that can impress us, what will make us more happy to use it and will protect our health is the quality of its water.

Good water quality is not a given but can be achieved with the correct design of the mechanical treatment plant, the selection of appropriate equipment, construction and organization of the operation of the pool. Unfortunately, the “invisible” mechanical installations are not always given the necessary attention. Many times they are the first victim of the need to cut costs. However, even in existing pools there are many possibilities for improvements in equipment and operation, which can dramatically improve water quality, possibilities that we are trying to highlight.

Pool water is constantly burdened by its use, by swimmers (sweat, urine) from air and water transport substances, a burden that must be neutralized in order for the water to continue to be suitable for swimming.

The conditions in the pool water favor the growth of microorganisms, many of which are pathogenic, such as coliforms, pseudomonas, legionella, cryptospores, amoebae. These organisms form colonies on the pool surfaces (walls, piping, filtration materials).

The increase in temperature triggers and the organic compounds feed the bacterial multiplication at rates of millions of times per day.


In nature, multiple treatment mechanisms work in the direction of neutralizing pollution and maintaining quality, such as water movement, ventilation, oxidation, filtration, etc. When these are not enough the quality degrades, such as swamp formation (stagnant water) , eutrophication etc.

In the pool, failure to clean with natural methods of water, leads to increased use of chemicals, although often this is not enough. Reckless use in turn creates its own burden, with the production of particularly dangerous substances (chloramines, chloroform, nitrates, isocyanurates, etc.).

The correct design of the mechanical installations of the pool is important for the utilization of natural processes for the necessary purification of the water and the limitation of the use of chemical substances. It focuses on prevention and not on control, on the elimination of the factors that favor the growth of microorganisms and not on the control after growth.

Important parameters in such a design are:

A. Filtration

The filtration function which should be as perfect as possible. Should be able to contain and dispose of as much of the pollution as possible. The choice of equipment, filtration material and processing rate are very important for the result.

Quartz sand has dominated for years as the ultimate filtration material. The ability of the sand to retain insoluble substances practically stops at the dimension of 20 μ.

Dryden Acqua has created an innovative material, the activated sand produced from recycled glass with selected characteristics (oxide metal content) for its activation, which is the basis for the natural treatment of the pool water.

Due to the activation treatment, the activated AFM sand does not allow microorganisms to settle and grow on its surface. This property is very important, as the huge cumulative surface of the sand grains is the main source of sedimentation and growth of microorganisms and the creation of Biofilm in a swimming pool.

An important parameter in the quality of filtration is the dimension of the filter that determines the speed at which water passes through the sand neither during the filtration process, nor during the reverse washing process. If this speed is outside the filtration limits, only unnecessary operation is performed.

Therefore the installation must enable us to measure and adjust the recirculation supply.

In any existing pool we can improve the filtration function with:

  • replacing the filter sand with activated glass sand
  • the installation of a flow meter and adjustment of the recirculation speed.

B. Design of recirculation pipelines

The filtered water should reach all parts of the pool, if possible evenly, so as not to create dead or reduced recirculation zones.

This need is served by the correct design of the piping, ie the arrangement of the orifices and the way of their connection.

The simplicity of the work often leads to the underestimation of the correct design and the empirical, without the necessary specialized knowledge, construction.

In existing pools it is usually difficult to intervene in the design of the piping and the margins for correction are small.

C. Operation

The most common question: “how many hours should the pool machines work”.

Under the pressure of reducing operating costs the answer is usually not the correct one, such as “interrupted every 4 hours”, “operation only closed during the day and night”, etc.

We know that in nature stagnant water, such as swamps, degrades rapidly and turns green. The same goes for the pool. So the answer to that question is that we want continuous operation at a reduced cost.

We can achieve both by operating the pool for half an hour during the remaining hours. Half-power operation requires 25% of power. We will also achieve electricity savings and better filtration and therefore a reduction in the need for chemicals.

It is a proposal that can be applied to any existing swimming pool with the appropriate modification of the mechanical installation in the engine room.

D. Use of chemicals

In a management, which aims at prevention and not control, the main use of chemicals is in the removal of chemicals, which are the food and the basis for the growth of microorganisms.

For this removal it is necessary to activate a process of conversion of solutes into insolubles and agglomeration into particles, which can be retained by the filter and removed. The procedure can be done with targeted use of chemicals. One such product, the APF of DRYDEN ACQUA, has a multiple action in the removal of organic substances, phosphorus compounds, bacteria, etc.

With the proper use of APF and good filtration, up to 80% of organic compounds and pollutants can be removed and thus reducing the need to use chemicals for oxidation to 20%.

The most common medium is chlorine. Chlorine in its reaction with organic compounds can under certain conditions produce annoying or toxic compounds.

But chlorine is not the strongest disinfectant. At the top of the list are free hydroxyl (OH-) radicals with twice the capacity of chlorine. Hydroxyl free radicals oxidize without creating any by-products. Their shelf life is a few seconds, so they must be produced in the pool.

There are several ways to produce free radicals, such as by splitting pool water. DRYDEN ACQUA ACO product blocks sunlight and then breaks down pool water to produce the hydroxyl free radicals needed for oxidation and disinfection.

Having removed all the pollutants and organic compounds, the use of a minimal amount of chlorine to give the water the necessary disinfectant capacity, does not produce any dangerous or annoying by-products.

A basic principle in the use of chemicals is that they work in strict dosage. Smaller quantities partially address the problem while larger ones are a waste.

Therefore, the correct and at the same time economical way is to do it with a dosing pump in combination with the continuous measurement of the requirement.

With the above changes and effective management we can swim in our pool in clean, safe and with drinking water specifications.

E. Savings

How can we finally reduce the operating costs of the pool? The answer by reducing operating hours does not lead to savings, but to higher costs for chemical treatment.

In any case, whether the pool is an investment or intended for individual use, ensuring the quality of the pool water is paramount.

But savings can be achieved by proper construction and operation, such as:

  • The correct design and dimensioning of the piping and equipment in the construction. For example, many times to reduce costs we reduce the cross section of the piping or do not pay due attention. Reducing the cross-section of the piping by half doubles the speed and quadruples the power required for recirculation.
  • Adjusting the operation of the pool (recirculation speed), so that during the day we have the necessary economic recirculation.
  • From the reduction of chemicals with the proper operation of the pool, which will reduce the need to use chemicals and from the correct dosing of them.

By investing in the proper operation of the pool, we multiply the added value of our investment.