A deeper look at Alkalinity, Part Two

The reason for a maximum level of total alkalinity is due to the fact that a level higher than 180 ppm also increases the possibility of scale forming. An exacerbating factor is that higher bicarbonate alkalinity can cause a more rapid upward drift in pH, due to the gradual loss of carbon dioxide from the water. It should to be understood that an alkalinity below 60 ppm or above 180 ppm does not necessarily mean that a corrosive or a scaling condition is imminent, only that the possibility of this condition is more likely. Other water balance parameters such as pH, calcium, and temperature may be able to counterbalance the out of range alkalinity level, although this is not a recommended way of maintaining water balance.

A low total alkalinity level can be quickly corrected by the addition of sodium bicarbonate (baking soda). Sodium bicarbonate increases the alkalinity level without affecting the pH significantly. Sodium carbonate (soda ash) also increases the alkalinity, even more than sodium bicarbonate (pound for pound). However, it may also raise the pH too high.

Too high of an alkalinity level can be corrected by adding muriatic acid or dry acid (sodium bisulfate), but will take more time because the acid has to be added slowly and in small increments.

Important Note: In regards to lowering alkalinity, there is NO truth to the concept that pouring acid in one spot of the pool (the column or “slugging” method) will result in a greater reduction of alkalinity than distributing the acid evenly around a pool. No matter how acid is added to the pool, it will always have the same effect on the alkalinity, as well as the pH. When manually adding acid to a pool, it is important to always dilute the acid and trickle it into the pool by walking around the perimeter. Acid is heavier than water and will sink to the lowest area of the pool, with the potential to damage (etch) the plaster surface, as well as the equipment if drawn in by the pump system. Pool operators should never pour undiluted acid into one area of the pool.

Source: Pool Genuis Network