Seawater systems scale formation

In fresh or brackish water cathode scale composition is even more variable than the scale formed in seawater since its formation is based on highly variable ion concentrations. This is also true in soils. Some soils will not form a visible scale, although there is enough calcium present in most soils to favor scale formation. Often, when a system has been polarized by CP, no scale will be visible until the system surface dries out. It then appears as a whitish coloration. On a buried system which has not been under CP, cathode scale is frequently found in an irregular mottled pattern this makes the actually active cathodic areas visible to the eye. 

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