ORP (Oxidation-Reduction Potential) is an important factor in pool water chemistry, especially for maintaining proper water sanitation. ORP measures the ability of a sanitizer (usually chlorine) to oxidize or disinfect contaminants in the water.
The ORP value is measured in millivolts (mV) and typically ranges from 0 mV to +700 mV. A higher ORP value indicates that the sanitizer is more effective at oxidizing contaminants, while a lower ORP value indicates that the sanitizer is less effective.
In a swimming pool, the recommended ORP value is between +650 and +750 mV. This ensures that there is enough sanitizer in the water to disinfect and oxidize contaminants, such as bacteria and algae, and maintain proper water clarity.
To maintain the proper ORP level in a pool, the Crystal Water Monitor sensors will take readings over 1000 times per week. If the ORP level is too low, the Crystal Water Monitor mobile app will recommend adding additional sanitizer to increase the ORP value. If the ORP level is too high, it may indicate that there is too much sanitizer in the water, which can cause skin and eye irritation for swimmers. In this case, diluting the water or reducing the amount of sanitizer added can help bring the ORP level back into the recommended range.
If you compare the Crystal Water Monitor ORP levels to that of a different meter, you will likely see different results. This is due to the following reasons:
- There is normal and expected variance across ORP meters - it is sometimes more than 100 mV. Each sensor can have local experiences in the water and sensors can take 10s of minutes to hours to fully acclimate and provide a valid ORP reading.
- Crystal Water Monitor is a monitor, not a meter. It looks at averages and trends, rather than just looking at a point in time. This provides a more realistic view of the chemistry of your pool or hot tub water, and filters out the occasional spurious results that may happen with individual readings.
- ORP readings ramp up and slowly level off. They can take many minutes, or even hours, to level off. Because the Crystal Water Monitor is battery operated, it only samples for a few seconds. We know the ORP will continue to ramp up, perhaps another 120 mV or so, but after a few seconds, we have a good sense of the water chemistry. We lower the target threshold for ORP to take this into account so your water does not get over-chemicalized.