In Northern latitudes, active oxygen is a particularly popular alternative disinfectant to chlorine. Principally, however, for purposes of measurement what counts is whether the medium used contains persulfate or peroxide. Water disinfected with persulfate-containing media is measured according to the DPD N° 4 method. When using peroxide containing disinfection media, Hydrogen Peroxide tablets are used in connection with the Acidifying PT tablets. In both cases, the “Active Oxygen (O2)“ designation is in fact misleading. It is not the molecular Oxygen that oxidizes (disinfects); rather it is an Oxygen radical which quite quickly combines with an additional radical to form molecular Oxygen (the air one breathes). This is also the main disadvantage to this method; because the disinfection effect does not last long and the effect is rather limited. As a strict rule, therefore, Chlorine is added in regular intervals when Active Oxygen is used for disinfection. Yet with the DPD N° 4 method false readings can then result (when simultaneously using both Chlorine and Active Oxygen), because the potassium iodide contained in this tablet catalytically splits the persulfates and thus the sum of persulfate and chlorine is indicated

KS4,3 Acidity is also known as m-Alkalinity, Total Alkalinity, Hydrogen Carbonate Hardness, Acid Buffering Power, Temporary Hardness, … Alkalinity describes the ability of water to buffer the increase of ph value influencing chemicals (flocculants, disinfection media – e.g. chlorine products – lowering or raising pH). To provide a sufficient buffering effect, alkalinity should amount to at least 0.7 mol/m3 and/or mmol/l. This value represents the hydrogen carbonated materials dissolved in water. The buffering effect in the 4.2 – 8.2 pH range relies on a balance between hydrogen carbonate ions and carbon dioxide dissolved in water. Should chemicals that lower the pH value of water be added (acids), then the hydrogen carbonate ion combines with these to form carbonic acid (which in turn dissolves into carbon dioxide and water) and water. At a 4.3 pH value all hydrogen carbonate ions are depleted; thus the KS4,3 Acidity designation. Should in contrast chemicals be added that raise the pH value (bases), then hydrogen carbonate ions form again out of dissolved carbon dioxide and water. The modified relationship between dissolved carbon dioxide and hydrogen carbonate ions thus determines a new pH value. The buffering capacity of water becomes too low at alkalinities below 0.7 mmol/l, thus making it difficult to determine the pH value. In such cases small amounts of acids and bases will immediately and intensively change the pH value. Furthermore, water will have a corrosive effect on pipe mains. An alkalinity value which is too low can be increased through the addition of sodium hydrogen carbonate and/or sodium carbonate. When alkalinity values are high, however, the buffering effect is too large and large amounts of pH regulators are needed in order to achieve a change in pH. Additionally, when conditions are unfavorable (warming, pH > 8.2), calcium tends to precipitate because carbonate ions form out of hydrogen carbonate ions which in turn form water-insoluble compounds in the presence of calcium or magnesium (see Total Hardness). Alkalinity that is too high can be corrected through – at least partial – replacement of water. Because pH values above 8.2 will stop the equilibrium between hydrogen carbonate ions and carbonate ions, the alkalinity of the water must then (pH value over 8.2) be measured with the Alkalinity-P method.

Aluminum is a silvery white, flexible alloy that is covered with an oxide layer in the air. Salt formation is made up from acids and bases, in this case mostly trivalent, and rarely monovalent. With approximately 8% in the earth’s crust, it is the most abundant metal and third most abundant element in the earth's crust. Aluminum is attained from bauxite, feldspar, mica, and clays. It is used technically as an alloying element for steels, bronzes, deoxidizers, for paint, reflectors and welding. Aluminum compounds are used as flocculants and as a flocculating agent in water treatment. Aluminum compounds are also used in medical products and cosmetics. The entry of aluminum into drinking water can be caused by insufficient flocculation, dissolution processes from soils, acid rain or waste water, and from the aluminum processing industry. Aluminium is in groundwater concentrations at 0.01 - 0.1 mg / L. The average daily intake via drinking water is at 0.5 mg / day. Drinking water regulations limit: 0.200 mg / L.

Ammonium ion NH4 + is a cation, which chemically reacts similarly to alkali metal ions, and forms salts of corresponding formula, such as ammonium nitrate (ammonium nitrate) NH4NO3 or ammonia (ammonium chloride). It is the conjugated acid base for ammonia NH3. It is not to be confused with quaternary ammonium compounds, in which nitrogen also has four binding partners, however these are all organic residues and not hydrogen atoms. In the natural environment however, ammonia results primarily in the degradation of proteins. It is excreted by fish and most other aquatic organisms as an end product, for example, via the gills. It is even released as an end product with the bacterial decay of dead biomass as an end product. It plays an important role in the citric acid cycle, in which it reacts with alpha-ketoglutarate to glutamic acid. Ammonium is, firstly to nitrite and other types of bacteria (Nitrobacter) to Nitrate, further oxidized and thus "detoxified" in the soil, and in areas under oxygen consumption from bacteria (Nitrosomonas). In addition to bacteria, archaea also plays an important role in ammonium oxidation in soil. [3] This process is called nitrification and is thoroughly desirable in soil. Nitrification is also an important part of self-purification in water. Ammonia is toxic to fish even at low concentrations. Ammonium content in water of 0.5 to 1 mg / l, therefore, depending on the pH of the water, is regarded as questionable for fish life. Ammonium levels at above 1 mg / l in waters is not suitable for fishing purposes.

Using bromine as a disinfectant is becoming a popular alternative to chlorine. The advantage of this method is that combined bromine is unscented compared to combined chlorine (chloramine). That is, the disinfection effect is the same but human mucous membranes are not irritated. Disadvantages to the use of bromine products include, however, the limited oxidation effect and the higher prices and handling risks. Often a combination of bromine and chlorine is used; but this makes determining the concentration difficult. Under the DPD N° 1 method, measurements now show (if chlorine is used with bromine) the total concentration of free and total bromine and free chlorine. In order to establish the bromine concentration in this special case, the free chlorine must be converted into combined chlorine with the aid of DPD-glycine. In contrast to chlorine, the confirmation “DPD N° 1” reagent works with both free and combined bromine, thus always establishing the total bromine content.

Basically dissolved salts belonging to the alkaline earth elements calcium and magnesium are found in non-distilled water. In rare cases, strontium and barium can also be found. These combine with carbonate ions to form water- insoluble compounds (calcium). Through the total hardness measurement, the potential danger of calcium precipitation is measured as the required carbonate ions form from hydrogen carbonate ions when water heats up or when there are pH values that are greater than 8.2 (comp. Alkalinity). When measuring calcium hardness (SVZ1300 tablet process), only the part of the dissolved calcium in water is measured. The amount of magnesium dissolved in water is determined from the difference between the measurement and the total hardness.

Chlorine (in the form of sodium hypochlorite, calcium hypochlorite, chlorine gas, chlorinated isocyanurates, ...) has prevailed worldwide as the leading disinfectant for swimming and bathing pools. To measure chlorine concentration existing in water under DIN EN 7393, 3 partial values are to be distinguished. 1.) free chlorine: chlorine that is present as hypochloric acid, hypochlorite ions, or dissolved, elementary, chlorine. 2.) combined chlorine: Portion of total chlorine which is present in the form of chloramines and all chlorinated derivatives of organic nitrogen compounds. 3.) total chlorine: Sum of the other two mentioned forms. While free chlorine immediately creates a disinfection effect, the disinfection potential of combined chlorine is highly limited. Chloramines are responsible for the smell of swimming pools and the irritation of human mucous membranes that lead to red eye. A member of this class of substances is nitrogen chloride which humans already perceive at a concentration of 0.02 mg/l. Free chlorine is measured according to the DPD N° 1 method. Here N,N-diallyl p-phenyl diamine (DPD), an indicator chemical, is oxidized by chlorine and discolors to red. The more intensive the discoloration, the more chlorine is present in the water. Photometric measurements or optical comparison with a colour scale allow the chlorine concentration to be measured. If a DPD N° 3 tablet is now added to this sample, then the combined chlorine will also be marked. The measured value now corresponds also to the total chlorine concentration. The concentration of combined chlorine corresponds to the difference between total chlorine and free chlorine. Since the slightest traces of the active chemicals in DPD N° 3 tablets lead to combined chlorine becoming active during the measurement, absolute care must be taken prior to the next DPD N° 1 measurement to sufficiently clean the measurement device thus avoiding false readings. The use of two differently calibrated vessels (one generally for measuring free chlorine and the other for measuring total chlorine values) is highly recommended.

Chlorine (in the form of sodium hypochlorite, calcium hypochlorite, chlorine gas, chlorinated isocyanurates, ...) has prevailed worldwide as the leading disinfectant for swimming and bathing pools. To measure chlorine concentration existing in water under DIN EN 7393, 3 partial values are to be distinguished. 1.) free chlorine: chlorine that is present as hypochloric acid, hypochlorite ions, or dissolved, elementary, chlorine. 2.) combined chlorine: Portion of total chlorine which is present in the form of chloramines and all chlorinated derivatives of organic nitrogen compounds. 3.) total chlorine: Sum of the other two mentioned forms. While free chlorine immediately creates a disinfection effect, the disinfection potential of combined chlorine is highly limited. Chloramines are responsible for the smell of swimming pools and the irritation of human mucous membranes that lead to red eye. A member of this class of substances is nitrogen chloride which humans already perceive at a concentration of 0.02 mg/l. Free chlorine is measured according to the DPD N° 1 method. Here N,N-diallyl p-phenyl diamine (DPD), an indicator chemical, is oxidized by chlorine and discolors to red. The more intensive the discoloration, the more chlorine is present in the water. Photometric measurements or optical comparison with a colour scale allow the chlorine concentration to be measured. If a DPD N° 3 tablet is now added to this sample, then the combined chlorine will also be marked. The measured value now corresponds also to the total chlorine concentration. The concentration of combined chlorine corresponds to the difference between total chlorine and free chlorine. Since the slightest traces of the active chemicals in DPD N° 3 tablets lead to combined chlorine becoming active during the measurement, absolute care must be taken prior to the next DPD N° 1 measurement to sufficiently clean the measurement device thus avoiding false readings. The use of two differently calibrated vessels (one generally for measuring free chlorine and the other for measuring total chlorine values) is highly recommended.

Chlorine dioxide (2.33 times heavier than air) is known as a gaseous compound of the halogen, chlorine, and oxygen (ClO2); which has the advantage over pure chlorine that it effects smell and taste perception less and that is also acts as an anti-virus. Chlorine dioxide is also manufactured at special facilities near the production site by combining chlorine gas and/or under-chlorinated acid and a fluid sodium chlorite solution (NaClO2) (10:1). On average 0.05 mg/l – 0.2 mg/l are assumed as average minimum/maximum values.

There can be different reasons for measuring copper values. When it comes to drinking water, copper measurements are made in order to determine the quality of the drinking water. There are no official maximum permissible values for copper in drinking water, but there are recommended values of between 2 to 3 mg/l. Copper is a trace element and is thus essential to human life. A daily consumption of 0.05 – 0.5 mg/kg body weight is considered acceptable. Copper is, however, considered to be dangerous to organisms which is “positively” taken advantage of in swimming pool areas to combat algae and bacteria in the form of copper-containing algicides. However, copper-sulfate containing algicides also have their disadvantages such as the possible discoloration of hair, spotting in swimming suits, and even corrosiveness and copper acetate sedimentation. As an example, copper releases into the drinking water from copper pipes. The “Copper/Zinc LR” tablet simultaneously measures both copper and zinc which is how zinc is eliminated from the reaction through the EDTA tablet included in the kit before both individual values are obtained. The “Dechlor” tablet prevents deviations in the measurement if the residual chlorine content is high.

When using organic chlorine products (trichlorisocyanuric acid and sodium dichlorisocyanurate), the so-called “isocyanuric acid” creates the carrier for chlorine. While the advantage of organic chlorine products clearly lies in the higher portion of active chlorine (up to 90%), the isocyanuric acid carrier substance can limit the speed at which the chlorine can kill off the bacteria when the concentration in water is high (>50 mg/l). It is thus recommended that one measure the cyanuric acid just as regularly as the chlorine content of the pool, in order not to counteract this fact by adding more chlorine (thus leading to higher isocyanuric acid being added).

In Northern latitudes, active oxygen is a particularly popular alternative disinfectant to chlorine. Principally, however, for the purposes of measurement what counts is whether the medium used contains persulfate or peroxide. Water disinfected with persulfate-containing media is measured according to the DPD N° 4 method. When using peroxide containing disinfection media, Hydrogen Peroxide tablets are used in connection with the Acidifying PT tablets. In both cases, the “Active Oxygen (O2)“ designation is in fact misleading. It is not the molecular Oxygen that oxidizes (disinfects); rather it is an Oxygen radical which quite quickly combines with an additional radical to form molecular Oxygen (the air one breathes). This is also the main disadvantage to this method; because the disinfection effect does not last long and the effect is rather limited. As a strict rule, therefore, Chlorine is added in regular intervals when Active Oxygen is used for disinfection. Yet with the DPD N° 4 method false readings can then result (when simultaneously using both Chlorine and Active Oxygen), because the potassium iodide contained in this tablet catalytically splits the persulfates and thus the sum of persulfate and chlorine is indicated.

In Northern latitudes, active oxygen is a particularly popular alternative disinfectant to chlorine. Principally, however, for the purposes of measurement what counts is whether the medium used contains persulfate or peroxide. Water disinfected with persulfate-containing media is measured according to the DPD N° 4 method. When using peroxide containing disinfection media, Hydrogen Peroxide tablets are used in connection with the Acidifying PT tablets. In both cases, the “Active Oxygen (O2)“ designation is in fact misleading. It is not the molecular Oxygen that oxidizes (disinfects); rather it is an Oxygen radical which quite quickly combines with an additional radical to form molecular Oxygen (the air one breathes). This is also the main disadvantage to this method; because the disinfection effect does not last long and the effect is rather limited. As a strict rule, therefore, Chlorine is added in regular intervals when Active Oxygen is used for disinfection. Yet with the DPD N° 4 method false readings can then result (when simultaneously using both Chlorine and Active Oxygen), because the potassium iodide contained in this tablet catalytically splits the persulfates and thus the sum of persulfate and chlorine is indicated.

Iron is normally attained via ferrous pipes into drinking water. Although these are often covered with a protective layer of zinc, which is designed to prevent corrosion (rust), the increases of iron in the water causes the gradual erosion of the zinc layer (see explanation on zinc). The limit for drinking water (in accordance with drinking water regulations->DWR) is 0.2 mg / l (= milligrams per litre, 1 milligram = 1 thousandth of a gram). The iron content limit fixed for DWR is meant, in this particular case, as a technical requirement for the protection against deposits in tanks and pipes. Iron content in drinking water is usually much lower than what is regarded for people as being the harmful limit of 200 mg. However a level of more than 0.2 mg / can already cause unpleasant effects to occur because iron ions flocculate visibly upon contact with dissolved oxygen. Staining, turbidity, sediment, and a rusty and metallic taste, are consequences of this process. For these reasons, often even small amounts of iron are disturbing.

Nitrate and nitrite are nutrients for plants, which have been used for many years as a fertilizer in agriculture, and also in small gardens, etc. Nitrate and nitrite are convertible with one other, depending on the oxygen content in the water. The cause of health risks is the risk of a reduction of nitrate to nitrite. Such a conversion takes place in the intestines through certain bacteria. Secondly, the salivary glands can, via the blood vessels, reduce stranded nitrate. The current limit for NO3-in drinking water is, according to German drinking water regulations, at 50 mg / l, and according to the Swiss Water Protection Regulations, at 25 mg / l, waters that exceed this limit are, often mixed with low-nitrate water in order to reach this limit. Recently, the first water treatment systems have been built using reverse osmosis or nanofiltration in order for the lower partial demineralization of the nitrate level in drinking water.

Ozone is comprised of 3 oxygen atoms (O3). It is an unstable molecule and disintegrates, after a rather short time either in the air or when it is dissolved in water, into oxygen, O2 and an oxygen radical. The oxidative effect of this oxygen radical is very strong and a depot effect is ruled out because two radicals immediately combine to O2. Ozone is produced directly on the spot by ozone producers and other required appliance-like devices. Special rules and precautions are required, because Ozone is 10 times more poisonous than chlorine. Thus Ozone is only used during a single dosage stretch – outside the pool – and must be filtered out before being used again (activated carbon). The maximum allowable concentration of ozone added to the pool is only 0.05 mg/l which is why ozone is insufficient as a disinfectant requiring it to be supplemented by other – as a rule chlorine content – disinfectants. Ozone kills bacteria, oxidizes organic contamination (e.g. urea), reduces chlorine usage, and leaves no irritating traces behind. As a rule, the human nose which can perceive ozone concentrations of 1:500.000 is the best measuring device. However, ozone combined with chlorine can be measured under the DPD method. By adding glycine, ozone is eliminated so that chlorine alone can be measured whereby the ozone content is determined from the difference.

The pH (potentia Hydrogenii) value is a measure of the strength of the acidic and/or base effect of a watery solution. It is particularly important when preparing bathing water because, among other things, it influences the effectiveness of disinfectants and the compatibility of the water with skin, eyes, and materials. A pH value of 5.5 is ideal for the skin. However, the water would then have so much acid that metallic materials would not only corrode but eyes would start to burn because tears have a pH value of between 7.0 and 7.5. therefore, a compromise must be found. In regard to materials compatibility, the pH value shouldn’t fall below 7.0 in any case. At the same time pH values over 7.6 will have dermatological effects and will also influence the effectiveness of the disinfectant, thus negatively influencing the speed at with which bacteria can be killed off. Principally: At pH values above 7.5 = the natural coat of the skin that protects against acids begins to be destroyed (>8.0); in (medium) hard water, calcium precipitation beings (>8.0); the disinfecting effect of chlorine declines with (>7.5) pH values under 7.0 = chloramines form which irritate the mucous membranes and cause irritations to the sense of smell (<7.0); corrosion appearances in metal-content (installed) parts (<6.5); problems with flocculation (<6.2).

Biguanide disinfectants are also gaining in popularity as an alternative to chlorine. Other than with other substitute materials, such as for example ozone or active oxygen, biguanides do not go well with chlorine, bromine, copper, or silver compounds. Nevertheless a counteracting agent is required because biguanides do not deploy an oxidative effect which is required, for example, for the breakdown of organic materials such as ureas and sweat. To do this, as a rule, hydrogen peroxide (H2O2) is used in addition to biguanide.

Phosphates come up in nature in multiple ways, for example after it rains in the hills. But detergents also use phosphates as softeners. Phosphates are basically non-poisonous, even encourage the growth of aquatic plants and thus also algae, which are really not welcome in pools. When present in water, phosphates can be removed with “Phosphate Remover” products such as, the “Accepta 9079”.

Being the seventh most abundant element, potassium is represented by 2.6% of the earth's crust. In groundwater K + ions are usually included in much smaller amounts than Na + ions as potassium is an important nutrient for plants. The human need for potassium is about 2 - 3 g per day. The effects on water and pipe networks are not known for potassium.

Sulphates such as gypsum, anhydrite, etc. are widely found in the natural environment. Groundwater contains for this reason 10-30 mg / litre sulphate. Sulphates are also components of chemical fertilizers, pesticides and detergents. Aluminum and iron sulfate are used in water treatment. Sulphate enters the water cycle via industrial waste water, for example from paper mills and textile factories. Sulphates are among the safest substances in water, but can the cause corrosion of water pipes. Waters containing large amounts of sulfate can be damaging to cement (sulphate flowering). A high sulfate content in conjunction with a high magnesium content such as tea and coffee leads to a deterioration of flavour. The maximum concentration is 250 mg / litre of drinking water.

Basically dissolved salts belonging to the alkaline earth elements calcium and magnesium are found in non-distilled water. In rare cases, strontium and barium can also be found. These combine with carbonate ions to form water- insoluble compounds (calcium). Through the total hardness measurement, the potential danger of calcium precipitation is measured as the required carbonate ions form from hydrogen carbonate ions when water heats up or when there are pH values that are greater than 8.2 (comp. Alkalinity). When measuring calcium hardness (SVZ1300 tablet process), only the part of the dissolved calcium in water is measured. The amount of magnesium dissolved in water is determined from the difference between the measurement and the total hardness.

There can be different reasons for measuring copper values. When it comes to drinking water, copper measurements are made in order to determine the quality of the drinking water. There are no official maximum permissible values for copper in drinking water, but there are recommended values of between 2 to 3 mg/l. Copper is a trace element and is thus essential to human life. A daily consumption of 0.05 – 0.5 mg/kg body weight is considered acceptable. Copper is, however, considered to be dangerous to organisms which is “positively” taken advantage of in swimming pool areas to combat algae and bacteria in the form of copper-containing algicides. However, copper-sulfate containing algicides also have their disadvantages such as the possible discoloration of hair, spotting in swimming suits, and even corrosiveness and copper acetate sedimentation. As an example, copper releases into the drinking water from copper pipes. The “Copper/Zinc LR” tablet simultaneously measures both copper and zinc which is how zinc is eliminated from the reaction through the EDTA tablet included in the kit before both individual values are obtained. The “Dechlor” tablet that is also included in the kit prevents deviations in the measurement if the residual chlorine content is high.