Know When To Replace Your Chemistry Controller Sensors

In Blog, Controllers, Maintenance Tips by Aaron Donohue

When should you replace your chemistry controller probes/sensors?

Ask this question to 10 aquatics professionals and you may well get 10 different answers.

This may be due to the brand, the service contract, pool usage/how quickly they foul, sensor age and of course maintenance routines.

You might think that is a long list of factors to consider, but fortunately everything has a known average to it with the pool industry.

  • Most sealed sensors will last you an AVERAGE of 24 months
    • Usually most last between 12 – 36 months depending on quality, application and maintenance routines.
  • Most sealed sensors will also cost you an AVERAGE of about $200
    • The cheapest sensors usually run you around $100.00 and will last you about a year. The more expensive sensors will last you $200-$300 and will last you 2 – 3 years.

While these averages are a good rule of thumb, there are times when the cheaper sensors last longer than the more expensive ones, and times when the expensive ones fall flat on their face at month 2 (and that’s what warranty is for!) Usually though, those exceptions are going to come down to application and maintenance.

So, apart from age, how do you tell when to replace your sensor?  Simple…  Pay Attention!


Perform daily checks

As a general rule, I tell my clients to monitor their system with daily checks, this allows them to notice when a sensor is starting to read off and take action earlier.

Limit Calibrations
Make calibrations only when necessary (following factory directions) and keep records of every one. Over calibrating sensors, especially by multiple people, often leads to delayed diagnosis of a sensor that needs service or replacement and extends the amount of time you spend chasing the system!

Clean when your calibration cycle speeds up

Obviously this requires understanding what the “normal” calibration cycle is, which is where those records come in handy…

Clean sensors when your calibrating noticeably more frequently (25-50% more often for you data geeks out there).

Basic Maintenance

In general (and this does vary between systems) I use the 1/1/1 rule to outline standard maintenance on sensors and that is:

  • 1 x per month – Clean the sensors
  • 1 x per week – Calibrate the sensors *(if needed)
  • 1 x per day – Check the sensors *(more is ok too)

If there is ever a question of whether it is time to change the sensor, look at how much time you are spending chasing the chemistry, the readings and making calibrations.

How does that time at your wage compare to the cost of the sensor?

Once those costs start to line up with each other.. it’s time to replace the sensor!

Replace When necessary!

Once you’ve identified that the sensor needs to be replaced, don’t dawdle just do it!


There are times when replacement sensors are quite expensive, and understandably there is always (or almost always) a budget to consider.


When it comes to the main system that keeps your pool in compliance, safe and sanitary for your patrons.. do you really want to skimp?

After all, it is not worth the fines or creating an unsafe swimming environment for your patrons!


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