ph in Spas & Hot Tubs

pH

We use pH as an index to express how acidic or basic (alkaline) a solution is. The scientific definition of pH is “the negative logarithm of the hydrogen ion concentration”.

A pH greater than 7.0 is basic, and a pH lower than 7.0 is acidic. In spas, it is important to maintain the water in the slightly basic range of 7.0 to 7.8.

If pH Is low:

  The water can corrode surfaces, metal equipment or fixtures.

  Bathers can experience discomfort from burning eyes and itchy skin.

  Chlorine may dissipate more quickly.

  The water may cause pitting and etching of spa surfaces.

At pH 6.5 the water would be acidic enough to corrode the metal of the spa equipment and would be uncomfortable for bathers. 

If pH Is high:

  Calcium and metals tend to come out of solution, creating the potential for staining and scale formation. The calcium and metals will actually create deposits and discoloration on walls and equipment.

  Bathers can experience discomfort from burning eyes and itchy skin.

  High pH can contribute to cloudy water.

At pH 8.0 calcium in the water combines with carbonates to form calcium carbonate, CaCO3, or limescale.  CaCO3 can also form tiny particles which float in the water and give it a cloudy or turbid appearance.

Adjusting the pH

You should maintain pH levels within the ranges shown in the table.

[NB. You must ensure that your TA is within the recommended range for your chosen sanitiser before you adjust your pH.]