ORP stands for Oxidation-Reduction Potential, also called redox potential. It is a measure of the ability of water to oxidise substances (give up electrons) or reduce them (take up electrons). In an oxidation-reduction process, one molecule loses electrons while the other takes them up.<\/p>\n
The ORP value is expressed in millivolts (mV). The higher the ORP value, the stronger the oxidising capacity of the water and therefore the more effective the disinfection. A positive ORP value means that the water has an oxidising effect, which is essential for killing bacteria, viruses and other micro-organisms.<\/p>\n
In swimming pools<\/a>, ORP is used as the primary indicator of the disinfection capacity of the water. The World Health Organization (WHO) has for years regarded ORP as the most important parameter for checking whether water is microbiologically safe to swim in.<\/p>\n The big advantage of ORP over measuring free chlorine is that ORP measures the actual disinfecting power, not just the chlorine concentration. Two swimming pools with the same amount of free chlorine can have a different ORP value, depending on factors such as pH, temperature and the amount of organic material in the water. ORP therefore gives a more direct picture of how effectively the water is being disinfected.<\/p>\n For a safe and well-disinfected swimming pool, an ORP value between 650 and 750 mV is generally recommended. At a value below 650 mV, disinfection is insufficient and bacteria and algae can develop. The ideal ORP value is between 700 and 750 mV, provided the pH remains between 7.0 and 7.6.<\/p>\n An important point to note: ORP is strongly pH-dependent. When the pH rises, the ORP value falls, which means that at a higher pH you need more chlorine to maintain the same disinfecting power.<\/p>\n ORP is measured with an ORP probe<\/a> (also called a redox electrode). This probe consists of a precious metal (platinum or gold) as the measuring electrode and a reference electrode (usually Ag\/AgCl). The measurement is based on the potential difference between these two electrodes.<\/p>\n In practice, the ORP probe is placed in the pool water, often in a flow cell or directly in the pipes. Modern measuring systems also show pH and temperature alongside ORP, giving you a complete picture of the water quality.<\/p>\n There are two commonly used ways to disinfect pool water: dosing liquid chlorine and using salt electrolysis.<\/p>\n Liquid chlorine<\/strong> is added to the pool water as a ready-to-use product. This is a proven method that works quickly and directly. A disadvantage is that liquid chlorine often raises the pH, so you have to add pH minus to keep the water in balance. You will also use several drums of chlorine per season, which in itself makes it more expensive than salt electrolysis.<\/p>\n Salt electrolysis<\/strong>, on the other hand, produces chlorine on site. The pool water contains a low concentration of salt (sodium chloride). By means of electrolysis in an electrolysis cell, this salt is converted into chlorine, which then disinfects the water. An important advantage of salt electrolysis is that no storage or transport of liquid chlorine is needed. In addition, a salt electrolysis cell also destroys chloramines, which ensures pleasant water quality.<\/p>\n Both systems ultimately use chlorine as a disinfectant, but the way in which the chlorine is produced and dosed differs. For ORP control it makes no difference in principle: the ORP probe measures the resulting disinfecting power in both cases.<\/p>\n An ORP probe is a sensor that measures the oxidation-reduction potential of the water. The probe consists of a precious metal (platinum or gold) and a reference electrode. When the probe comes into contact with the pool water, a small potential difference arises, which is converted into an mV signal. <\/p>\n The Meytec NXG-ORP<\/a> probe is compatible with all common automatic dosing systems on the market that use the standard BNC connection. You can therefore use it as a replacement probe for Hayward, Sugar Valley, Zodiac, Seko, CCEI, Pool Technologie, Avady, Bayrol and more.<\/p>\n Both platinum and gold are used as the measuring electrode in ORP sensors. The choice between the two depends on the application:<\/p>\n Calibrating an ORP probe is essential to ensure accurate measurements. Unlike pH probes<\/a>, ORP probes need calibration somewhat less often, but you should check them regularly.<\/p>\n Calibration (or verification) is recommended:<\/p>\n The calibration procedure is as follows:<\/p>\n You must not reuse ORP buffer solution after use; pour it away and never reuse it.<\/p>\n ORP buffer solutions (also called redox calibration solutions) are available in various reference values. The most commonly used are:<\/p>\n Meytec supplies ORP buffer solutions in various packaging, including 250 ml bottles and handy sachets. For optimal shelf life, it is advisable to pour only a small amount into a clean glass or beaker for each calibration and to close the main bottle immediately after use.<\/p>\n Also take a look at our calibration packs<\/a>: with these you have everything, including pH and ORP buffer solution for calibrating your dosing system. The pack also includes cleaning and storage solution for electrodes to keep them in good condition.<\/p>\n Good maintenance of the ORP probe<\/a> is crucial for reliable measurements and a long service life.<\/p>\n With good maintenance and regular calibration, your ORP probe will keep measuring reliably for years, so that your pool water always stays safe and clear. Meytec offers a complete range of ORP probes, buffer solutions, cleaning agents and storage solutions to support you.<\/p>\n Related: pH probe.<\/p>\n","protected":false},"excerpt":{"rendered":" A clear and safe swimming pool starts with effective disinfection. In this blog we explain what ORP (oxidation-reduction potential) is, why this value is essential for pool water and how to measure ORP with an ORP probe. We discuss the difference between liquid chlorine and salt electrolysis, the choice between platinum and gold ORP probes, and how to calibrate the ORP probe with ORP buffer solutions.<\/p>\n","protected":false},"author":0,"featured_media":13921,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[549],"tags":[],"class_list":["post-17976","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog"],"permalink_manager":null,"_links":{"self":[{"href":"https:\/\/meytec.eu\/en-mt\/wp-json\/wp\/v2\/posts\/17976","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/meytec.eu\/en-mt\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/meytec.eu\/en-mt\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/meytec.eu\/en-mt\/wp-json\/wp\/v2\/comments?post=17976"}],"version-history":[{"count":1,"href":"https:\/\/meytec.eu\/en-mt\/wp-json\/wp\/v2\/posts\/17976\/revisions"}],"predecessor-version":[{"id":21872,"href":"https:\/\/meytec.eu\/en-mt\/wp-json\/wp\/v2\/posts\/17976\/revisions\/21872"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/meytec.eu\/en-mt\/wp-json\/wp\/v2\/media\/13921"}],"wp:attachment":[{"href":"https:\/\/meytec.eu\/en-mt\/wp-json\/wp\/v2\/media?parent=17976"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/meytec.eu\/en-mt\/wp-json\/wp\/v2\/categories?post=17976"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/meytec.eu\/en-mt\/wp-json\/wp\/v2\/tags?post=17976"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}How do you measure ORP?<\/h2>\n
How is disinfectant produced? The difference between liquid chlorine and salt electrolysis<\/h2>\n
Swimming pool ORP probe: what is it and how does it work?<\/h2>\n
Difference between platinum and gold<\/h3>\n
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Calibrating an ORP probe<\/h2>\n
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ORP buffer solutions<\/h2>\n
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Maintaining an ORP probe: cleaning and storage<\/h2>\n
Storage<\/h3>\n
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Cleaning<\/h3>\n
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