Why are pool heaters considered susceptible to scaling?

Pool heaters are particularly susceptible to scaling primarily due to the phenomenon where calcium carbonate tends to precipitate and form scale when water temperatures are elevated. As water is heated, the solubility of calcium carbonate decreases, leading to an increased likelihood of scaling on the heating elements and other surfaces within the heater. When the water temperature rises, calcium and carbonate ions in the water can combine to form solid calcium carbonate, which accumulates and creates deposits that can impair the efficiency of the heater and potentially damage it over time.

In contrast, low pH levels do not directly contribute to scaling; instead, they can lead to corrosion. Rapid evaporation primarily affects water levels and chemical concentrations but does not directly cause scaling. Poor circulation may contribute to localized temperature differences or imbalances in chemical levels but is not a primary factor in the formation of scale itself. Thus, the key aspect driving the susceptibility of pool heaters to scaling is the relationship between elevated temperatures and the formation of calcium carbonate.