The water treatment of each pool should always be carried out scrupulously and adapted to the needs of the pool type, through precise management and control systems designed to ensure the protection of bathers.
The treatments are normally carried out in two ways:
1) by filtration (or clarification, so as to eliminate the solid parts suspended in the water);
2) for chemical treatment: in order to obtain a safe disinfection (and therefore destroy the bacteria, microorganisms and organic products) and to control the hardness and pH of the water.
PARAMETERS TO CHECK
To obtain a water suitable for bathing, non-corrosive and without fouling it is necessary to keep 4 basic parameters under control:
1) the pH;
2) the hardness;
3) dissolved salts;
PH: pH gives the value of acidity or basicity (alkalinity) of water. The ideal value should be between 7.2 and 7.4. If the pH value is less than 7.0, the water is acidic and tends to corrode the metallic elements with which it comes into contact along its recirculation, moreover it causes burning of the mucous membranes and the eyes; If the pH is higher than 7.6, the basic (alkaline) water favors the development of bacterial flora and calcareous deposits and tends to remain cloudy.
The pH of a pool usually tends to increase over time:
increases rapidly with the use of basic products such as sodium hypochlorite or calcium hypochlorite).
In the range of pH 7.2 – 7.6 instead, the following benefits are considerable:
1. Chlorine works well because it is present both as indissociated hypochlorous acid and as dissociated acid. In this way there is both a quicker germicidal action and a slower but persistent one.
2. Water is not irritating to bathers in this pH range. Already under pH 7.2 the hypochlorous acid and chloramines, even if present in very small quantities, cause irritation to the eyes and mucous membranes of bathers.
3. The water is not corrosive and does not cause incrustations.
PH adjustment: when the value of pH super 7.6, it must be lowered with the use of pH-. On the other hand, when the pH is lower than 7.2, it must be increased by adding pH +.
defines the concentration of calcium and magnesium bicarbonates dissolved in water. Water that is too “hard” causes encrustations on the stairs, on the cladding and in the pipes. A water that is too “sweet” becomes aggressive and corrodes the metal parts, favoring, in the case of tiled pools, the dissolution of the lime with the consequent detachment of the tiles.
The hardness reduction must be carried out in extreme cases (in this case it can be used SEQUESTRANTE), while the raising is usually carried out with small amounts of calcium chloride.
The ideal value of hardness is in the range: 15-25 ° FI dissolved salts: are the ions of metals such as copper, iron and manganese that make the water opaque and colored when they are oxidized by chlorine (in the presence of iron to eg the water turns reddish brown). In this case it is possible to resort to small quantities of chelating and sequestering compounds. The ideal values (subject to variations) are in the range: 200-500mg / L.
it is the parameter usually less controlled is related to the total amount of salts dissolved in water. It represents the “buffer power” of water. Unstable alkalinity can cause undesirable effects: if the alkalinity is low, it is difficult to control the pH, because even small additions of correctors cause large changes in pH. On the other hand, if the alkalinity is too high, there is a risk of incrustations. The main substances that contribute to the alkalinity are carbonates, bicarbonates, hydroxides, and carbon dioxide. The pH value should take into account the alkalinity of the water. Calcareous water will need a low pH value closer to 7.2 to not encrust the walls, while a water with few dissolved salts or rainfall will need a pH value close to 7.6 to not irritate the eyes and mucous.
The disinfection of the pool water through chlorination is the most widespread method in the world for its relative simplicity and effectiveness. The value of free chlorine should be between 0.6 ppm and 1.50 ppm and should be uniform at any point in the tank. The treatments with products based on chlorine are divided into:
Shock or superclothing treatment: it must be done at the beginning of each season and must be repeated every two weeks for private pools and every 5/6 days for public pools. The shock treatment serves to eliminate the “chlorine resistance” of algae and bacteria and to oxidize all the contaminants present in the water brought by bathers (saliva, urine, sweat), insects, wind, atmospheric precipitation. Each pool, in relation to water and the degree of contamination, has its own “chlorine request” necessary to oxidize the various contaminants. The oxidation reaction leads initially to the formation of chloramines responsible for the annoying smell of chlorine and irritation to eyes and mucous membranes. If the amount of chlorine is sufficiently high, the chloramines and all other contaminants are oxidized and destroyed. The chlorine content to which this occurs is called: break-point.
After the break point, all the contaminants are eliminated and the chlorine still available (free) will act against any other contaminants that may occur. Keeping a free chlorine level between 0.6 ÷ 1.00 ppm in the water of the pool, you will have an optimal water from the hygienic point of view. The purpose of the super-chlorination is therefore to bring the chlorine in water over the break point. Obviously, after the shock treatment, it is necessary to wait for at least one filtration cycle before checking the level of free chlorine in the tank. Surely it will turn out to be a high value for which you will not need to add more chlorine until it has returned to normal. Shock treatment is essential in the summer when the increase in temperature tends to favor the proliferation of bacteria and algae. It is usually performed with rapidly dissolving chlorine (56% granular dichloroisocyanurate).
Chlorination treatment: this is the normal pool maintenance treatment. It is performed using 200 g slow-dissolving trichloroisocyanuric acid tablets, which can slowly but regularly increase the chlorine level, so as to oxidize the micro-organisms (bacteria, fungi, algae) present in the pool. Trichloroisocyanuric acid tablets, ideal for pools with large metal or masonry structures, can be inserted in the skimmer, in the lotion dissolvers or in the floating ones where they slowly dissolve, keeping constant the quantity of chlorine in the water. Under normal operating conditions, a free chlorine concentration between 0.6 ÷ 1.00 ppm must be recorded. If this concentration is not reached, it means that the number of tablets used is not sufficient. As an alternative to tablets, rapidly dissolving granular dichloroisocyanurate can be used.
Algae treatment: high temperatures, pH values higher than 7.6, and insufficient chlorination favor the proliferation of algae, black algae and bacteria that usually develop in places where water circulation is poor (edges, bottom pool). At the beginning of the season and at regular time intervals it is necessary to carry out this treatment by introducing the anti-algae product into the skimmer or, for pools on the spillway edge, into the compensation tank.
Flocculation treatment: this treatment assists the filtration process and serves to eliminate from the water those microscopic particles that create turbidity phenomena. The molecules of the flocculant, hydrating themselves, increase in volume and bind together forming reticulated flakes which, depositing themselves in the sand filter, increase their filtering power, allowing the latter to block even the smallest particles. The treatment must be carried out when the system is working by inputting the FLOCCULANT, suitably pre-diluted, directly into the skimmer or, for pools with a spillway edge, into the compensation tank close to the suction.