Gondo ORP Tester

ORP (Oxidation Reduction Potential), also known as Redox, measures the oxidizing or reducing power of water in millivolts (mV). In a swimming pool, it directly reflects the actual disinfection efficiency, regardless of the raw chlorine level. Water with a positive and high ORP is oxidizing and therefore disinfecting; water with an ORP close to 0 mV is neutral and does not effectively destroy bacteria. Measuring ORP ensures that your water is truly healthy, beyond simple chemical dosing.

Pool water is considered properly disinfected when the Redox potential is around 650 mV. The acceptable range is between 550 and 750 mV: below 550 mV, the disinfecting power is insufficient, and bacteria take longer to be eliminated. Above 750 mV, the water is too oxidizing, which can cause skin and eye irritation, as well as accelerated equipment degradation. The Gondo ORP tester allows you to check in real time that you stay within this optimal range.

The Gondo ORP tester offers an accuracy of ±2% with a resolution of 1 mV, over an extended measurement range of ±1999 mV. For example, for a measurement at 650 mV, the maximum error margin is approximately ±13 mV, which is largely sufficient to assess the sanitary condition of the water and make the right treatment decisions. This millivolt resolution allows for the detection of subtle changes in Redox potential, especially when adjusting the production of a chlorinator.

The Gondo ORP tester is a spot and portable measurement device: you use it to perform an on-demand check by immersing the electrode in the pool water. A continuously installed ORP probe (like those of CCEI Oxeo or Limpido regulators) is permanently immersed in the hydraulic circuit and transmits the value to the regulator in real time to automatically control disinfectant injection. The Gondo tester is ideal for checking the reliability of your fixed probe, performing spot checks, or diagnosing a disinfection problem.

Yes, the Gondo ORP tester is the ideal companion for a salt chlorinator. Chlorine produced by electrolysis generates a Redox potential in the water that directly reflects its disinfecting efficiency. By measuring ORP, you can verify that your chlorinator is producing enough active chlorine and adjust its production level if necessary. This is particularly useful after heavy swimming, a thunderstorm, or a heatwave, which can rapidly lower the Redox potential and require increased production.

The Gondo ORP tester is a versatile tool usable in many applications requiring the control of water's oxidizing power. It is suitable for spas and jacuzzis (where disinfectant monitoring is even more critical than in pools due to high temperatures), marine and freshwater aquariums (to control ozone or antioxidants), drinking water purification and treatment, and aquaculture. Its extended measurement range of ±1999 mV covers all these uses.

Turn on the tester and immerse the electrode in your pool water about 30 cm deep, away from return jets and chemical injection areas. Gently stir to remove air bubbles from the electrode. Wait for the displayed value to stabilize, which may take 30 to 60 seconds depending on conditions. For a representative result, perform the measurement when the filtration pump is running and the water is well circulated. Rinse the electrode with clear water after each use.

A low ORP despite an apparently correct chlorine level is often linked to the water's pH: a pH that is too high (above 7.6) drastically reduces the effectiveness of active chlorine without changing its total concentration. The first check to perform is therefore the pH — if it exceeds 7.6, lower it with pH- and the ORP will naturally rise. Other factors can also explain a low ORP: a high organic load (many swimmers, pollution), highly chlorinated water, or insufficient salt level in the case of a chlorinator.

These two Gondo testers are complementary and indispensable together. The pH 6011 tester measures the acidity or basicity of water (scale 0 to 14) — an incorrectly set pH reduces chlorine effectiveness even at correct dosage. The ORP tester directly measures the actual disinfection effectiveness in millivolts, regardless of the treatment method. For comprehensive and reliable management of your pool water, the combined use of both testers helps understand why the water is well or poorly disinfected and to act precisely.

During periods of heavy use, an ORP measurement 2 to 3 times a week is recommended, ideally at the end of the day after a day of swimming. An additional check is necessary after a thunderstorm (rain dilutes and acidifies the water), high heat (sun's UV degrades chlorine), or intense swimming (high organic load). If you have an automatic regulator with a Redox probe, the Gondo tester remains useful for periodically checking the consistency of your fixed probe's measurements.