ORP measures (REDOX)

The ORP measurement indicates the level of active disinfection in your pool or spa.

For optimal disinfection of water at 25°C, international standards recommend ORP / Redox measurements between 650 and 750mV.

On your ICO application, you can find the ORP trends by clicking on thetrend icon.

If action is required on your part, ICO will send you a recommendation.

Normal variations in ORP measures

Fluctuations in ORP measurements may be normal. Depending on the weather or swimming conditions, ICO may detect changes between two consecutive measurements.

However, it is normal to observe variations in your ORP readings, as this varies according to the UV and, above all, the pH of the water. If your measurements vary by +/- 50mV during the day in high season, there is not necessarily anything to be done. You simply need to check your pH and water temperature parameters regularly.

pH impact REDOX/ ORP measurement

In a chlorine pool, the higher the pH, the less effective the chlorine. Water disinfection - the ORP in this case - is consequently low. To summarize, the first thing to do when you notice a low ORP is to test the pH of your pool water. If the pH is above 7.6, then the pH is outside the optimum range (between 7,0 and 7.4). You'll need to lower the pH.

In a bromine or salt pool, it's the opposite of a chlorine pool. The higher the pH, the more effective and disinfectant the bromine. That's why the optimum pH threshold is higher: 7.2 and 7,6. If you have a bromine pool and your pH is low (below 7.4), this may explain why your ORP reading is too low. You'll need to increase pH level.

Possible ORP measurement anomalies :

Your ORP is low (<650 mV)

You have just filled your swimming pool or spa

• It is normal to have a low disinfection level if you have just filled your pool. ICO will soon make recommendations on how to increase the disinfection level.

Your pool or spa was already full

Check the pH

• If your pool is treated with chlorine, check the pH
  • if the pH > 7.6, you need to lower the pH in your pool
  • if the pH is between 7.2 and 7.6, the pool lacks disinfectant. You need to add chlorine

• If your pool is treated with bromine, check the pH
  • if the pH < 7.2, it is important to raise the pH in your pool
  • if the pH is between 7.5 and 7.8, your pool is lacking disinfectant. You need to add bromine

Votre ORP est haut (>850 mV)

Check the pH

As when the ORP is too low, you need to check the pH of your pool/spa water.

If the pH of the water is optimal, the solution to your ORP problem may lie in the stabiliser.

Check the level of stabiliser (cyanuric acid Cya)

In this case, you will need to measure your stabiliser level (using a test strip, for example):

• Result 0-30 ppm the pool/SPA does not have enough stabiliser, the REDOX drops very quickly when chlorine is added. You need to increase the stabiliser level to achieve perfect disinfection.
• 30-50 ppm measure: ideal rate for pool/ SPA
• 50-60 ppm measure : the level is high but still acceptable. You can simply change your disinfection method by using non-stabilised chlorine.
• Result > 60 ppm: The level is very high, you can drain part of the volume of water in the pool or SPA (by changing half the water, you will halve the stabiliser level) OR use a stabiliser reducer. 

Your ORP fluctuates

You observe a variation greater than 200 mV between two measurements: if you have not carried out a recent chemical treatment that could explain this large variation, contact our support service.

Too regular ORP fluctuations

In this case, it may indicate a fault in the treatment of your pool or spa.

Check the following information:

How filtration works.

• If your filter is not working properly or the filtration time is insufficient, the rate of disinfection will not be uniform in your pool or spa. The ORP level can also change depending on the position of your ICO in the pool.

• Clean the filter regularly and check the filtration system during weekly maintenance to ensure that the ORP is even in your pool.

The electrolyser

In salt-treated pools or spas, sometimes you just need to change the injection settings on your chlorinator to restore a stable ORP. Also, if the chlorinator malfunctions, the ORP (disinfection rate) will be unstable. Checking that it is working properly is part of the weekly maintenance recommended by Ondilo.

Your ORP measure seems wrong

Couldn't you find an explanation for this anomaly in the article? contact the helpdesk.

Your ORP sensor cannot be calibrated

Make sure you have followed all the calibration steps. If you still have a problem, contact our helpdesk.