ORP measures (REDOX)

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

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

Trend of changes in ORP measures

Sur votre application ICO, vous pouvez retrouver les tendances de l’ORP en cliquant sur l’trend icon.

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

Possible ORP measurement anomalies :

Your ORP is low

  1. You have just filled your pool or SPA: It is normal to have a low disinfection level if you have just filled your pool. ICO will soon be making recommendations on how to increase the level of disinfection.
  2. Your pool or spa was already full 

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 entre deux mesures : si vous n’avez pas réalisé de traitement chimique récent qui puisse expliquer cette grande variation, contactez 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.


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 sensor cannot be calibrated

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

Your ORP measure seems wrong

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

Other articles

Need more help ?