What are the correct cyanuric acid levels in a spa?

What are the correct cyanuric acid levels in a spa?

The correct levels of “Cyanuric Acid” in your spa sanitiser help protect against chlorine loss caused by sunlight.

The correct level of cyanuric acid in your spa water is between 30-50ppm

What is Cyanuric Acid?

Cyanuric acid, also called “stabilizer” or “conditioner,” makes chlorine more stable when exposed to the sun’s ultraviolet rays. It is like sunblock for your sanitiser, preventing it from degrading as quickly as it would otherwise. Without cyanuric acid, your chlorine level can drop from the ideal range to zero in less than two hours. On the other hand, if cyanuric acid is too high, it can cause a high level of total dissolved solids (TDS), and cause chlorine to be inefficient.

Two types of chlorine compounds, dichlor and trichlor, already contain some cyanuric acid. The level of cyanuric acid will build up with the continued use of either of these sanitisers. If using any other form of chlorine, you will need to add cyanuric acid separately in order to stabilize the chlorine. The acceptable level of cyanuric acid is 30 to 150 ppm (except where 100 ppm maximum is regulated by the health department), with an ideal level of 30 to 50 ppm (mg/L).

When your cyanuric levels are too high, you have three options:
  1. Purchase a cyanuric acid reducer (not always effective and can interfere with your water balance)
  2. Completely drain and refill with new water 
  3. Partially drain and add some fresh water (For example; if your cyanuric acid level is 5% too high, then you need to remove about 5% of the spa water. )

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