TH and pH are part of the three factors that determine the equilibrium of your water with TAC. They allow you to keep a clear water throughout the season. To enlighten you and help you to differentiate them, find all the information to remember in this article. 


TDS (Total Dissolved Solids)

ICO measures the TDS level every hour because too high a concentration of trace elements (Iron, Chlorine, Bromine) and minerals (Calcium, Phosphates or Carbonates) are responsible for the appearance of limescale which clouds the water and damages the equipment to the point of causing the appearance of algae. Conversely, if the TDS is too low, the water can irritate the skin and eyes. ICO adapts its recommendations according to your water treatment.


The tH corresponds to the hardness of the water, which designates its concentration of limestone (this is called the alkalinity rate of the water). It is measured in French degrees (°F) and is ideal between 10 and 20°F. ( 100 to 200 mg/l or ppm). Indeed, the higher the tH, the harder the water, i.e. the more calcareous it is. On the other hand, the lower the tH, the softer the water.

How to regulate the tH of your pool?

With hard water (above 20°F / 200 mg/l or ppm): First, pay attention to the temperature of your pool water, which will promote scale formation if it is high. Secondly, regulate the pH of your pool between 7.2 and 7.4. Finally, if you can, add a sequestering product to slow down the formation of limescale.

With soft water (below 10°F / 100 mg/l or ppm): Use a product to increase the tH to 15°F and then adjust the pH of your pool.


The TAC or Complete Alkalinity Titer, measures the alkalinity of water to know its concentration in carbonate and bicarbonate ions. This measurement indicates the capacity of the water to absorb pH fluctuations and be able to stabilize it. The unit of measurement for the TAC level is the ppm (part per million) or the French degree (°f). By regulating the TAC level of your water (TAC+ or TAC-) you can do what is called “buffering your water”.

The pH

The pH corresponds to the acidity of the water and is measured on a scale of 0 to 14. The pH of drinking water is usually between 6.5 and 8.5. However, for your pool water, it is ideal between 7.2 and 7.4. The pH is evaluated on 3 levels:

  • A pH below 6.5 means that your water is acidic
  • A pH equal to 7 means that the water is neutral
  • A pH higher than 7.6 means that your water is basic


How to regulate the pH of your pool or spa ?

  • If it is too high (8 and 14): Use a pH minus product, respecting the doses provided. After pouring it into the water, wait a few hours (minimum 6 hours) before testing the pH of your water.
  • If it is too low (between 0 and 6): Acidic water makes bathing uncomfortable. Contrary to the above instructions, use a pH plus product. During this manipulation, be sure to leave your filtration system running and wait at least 6 hours before testing your water again.



To conclude, regulate your pool water regularly so that you can act in time to enjoy your swimming moments.

To conclude, check the quality of water in your pool regularly to be able to act in time to be able to make the most of your swims. 

ICO’s advice :


I am ICO, your connected island which measures, anticipates, and changes your advice and lets you know on your smartphone. 

Thanks to my sensors, I give you the following information directly through your smartphone: pH through the blue sensor, Redox (rate of disinfectant) and estimation of chlorine level) through the orange sensor, and the conductivity through the grey sensor.

I also provide other estimations like salt level and alkalinity (TAC).

Pour garder une eau équilibrée, inoffensive pour la peau comme vos équipements, il faut traiter avec le bon soin au bon dosage.

More information about water hardness

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