WHAT TO KNOW ABOUT PLASTER:

Plaster has a porous surface, which makes it susceptible to staining, bacteria growth and breakdown by the chemicals you add. Because plaster constantly reacts to water and chemicals, plaster pools "use" more chemicals to maintain a balanced water chemistry. You can expect a new plaster surface to give you 7 to 10 years of good service with proper care.

Plaster has shading variations, known as mottling, and distinct from surface stains and deposits, mottling may appear as grayish hued areas. Rarely do I see a plaster job that is white like milk. They're usually white like clouds. Being a natural product, mottling is inherent in any plaster job and should not be considered a defect. There has been much research on the subject in recent years, however no consensus has been reached on the causes and cure of mottling.



PLASTER STAINING AND HOW TO AVOID:

Want to increase the life of your plaster? Barring problems in the mixing, application and curing processes, the pool owner, or service company controls its condition and life span. Keeping your water chemistry in balance and most importantly, preventing corrosive water environments of low pH and low alkalinity will reduce wear and tear.

1. Most stains are caused by heavy metal minerals coming out of solution and depositing themselves on the nearest structure they find. They may also remain suspended in water, providing dramatic new color schemes. Below is a list of common metals found in pools, where they came from, and their identifying colors

COLOR OF STAINS AND WHAT COULD BE CAUSING THEM:

White, Crystals or Precipitate - Metal: Calcium - Source: Plaster, Grout Mortar

Red, Blue, Gray or Black - Metal: Cobalt - Source: Fiberglass Shells

Blue, Green and Blue-Green - Metal: Copper - Source: Copper Algaecidies, Ionizers, Corrossion of copper and brass pipes, fittings and heaters.

Dark Red, Brown, Black, Grey or Green - Metal: Iron - Source: Well water, corrossion of iron pipe and fittings

Pink, Red or Black - Metal: Manganese - Source: Well Water

2. If any of the above causes apply to you, your pool should be using a sequestering agent which aids your water balance in preventing the metal from dropping out of solution and staining underwater surfaces. Most stains left by precipitated metals can be removed by one form or another.

3. Metallic salts cause scale. These salts are primarily forms of calcium and magnesium which can deposit on your plaster, pipes and equipment. They may arise from the use of calcium based sanitizers or the fill water may have high calcium hardness levels.

4. Keep your calcium hardness levels between 200-400 ppm. A level that is above this may find it easy to precipitate out of solution. This is known as a scaling condition. Conversely, water with low levels of hardness will produce an aggressive condition. In aggressive conditions (soft water), the water will take the calcium it wants directly out of your plaster, resulting in plaster breakdown and bond failure.

Labels: concrete in pools, copper pool stain, how to avoid plaster stains, iron pool stain, metal pool stain, metal staining in plaster, plaster staining, plaster stains, pool plaster, replaster