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Problems due to Contamination in the pool water


Most people assess the well-being of a swimming pool by what they can see: the clarity of the water and the appearance of its surfaces. There are many common issues that lead to staining in pools, and a few not-so-well-known causes.

Water balance

Most stains and discoloration can be traced to improperly balanced water. But even “perfectly balanced” pools have the potential to contribute to these types of problems due to the almost-daily influx of metals, minerals and other contaminants.

Staining and discoloration can be broken down into two main categories: organic and inorganic.

  • Common organic causes include scale, algae, “pink slime,” white water mold and vinyl liner mold.
  • Inorganic causes include scum-line buildup, cloudy or tinted water and iron and copper stains.

Lesser-known causes of staining

Copper combined with high level of stabilizer,” creates a purple precipitant. This purple stain is bright and highly visible, often showing up on tile, spillways and pool cleaners.

Another potential stain-causer is potassium permanganate which creates a pink/purple stain when it comes in contact with the pool finish.

Iron and scale are two common causes of staining in a pool, known as iron scale this is a tough stain that can be particularly difficult to remove, as standard treatment doesn’t often work.

Calcium Hardness is the measure of calcium in the water. Water must have a certain amount of calcium in it for it to be “balanced with the other elements”. The goal is neutral or inert water. Without calcium this cannot be accomplished.

Low Calcium will cause:

  • Difficulty of balancing water
  • Etching of plaster
  • Corrosion of metal components
  • Eye and skin irritation
  • Water foaming

High Calcium will cause:

  • Scale Formation on pool surface and equipment
  • Cloudy water
  • Eye & skin irritation
  • Difficulty balancing water
  • Chemicals become less effective
  • Ideal range: 200—400 ppm (mg/l)

Organic problems such as algae and bacteria can discolor the water and deposit themselves on pool surfaces in a rainbow of greens, blacks, yellows and pinks. Algae deposition is distinguishable from stains as they are on the surface and not impregnated into the plaster.

Other organic materials such as leaves, worms, or other vegetable matter can also stain pool plaster.

Inorganic materials like copper, iron, magnesium, calcium or aluminum can also cloud or discolor the pool water and stain or scale the pool surfaces, especially the plaster and tile grout. When a precipitated metallic salt such as calcium or magnesium remains in suspension, it can cause turbidity or cloudiness of the water. When heavy metal minerals are in suspension, they'll color the water. When these minerals stop floating around and get deposited on interior pool surfaces, the mineral salts such as carbonates of magnesium and calcium form a whitish crystallized deposit known as scale. If the precipitated minerals have color, as heavy metals often do, they get deposited in the form of a stain.

Algae are a living aquatic creature that multiplies rapidly on warm, sunny days. Containing chlorophyll, algae utilizes photosynthesis to grow. That is, they take in carbon dioxide and expend oxygen as a byproduct.

Algae spores constantly enter the pool, brought in by wind, rain or even contaminated swimsuits or equipment. When conditions are right, an algae bloom can occur seemingly overnight. These conditions include out of balance water, warm temperatures, sunlight and presence of nitrates and/or carbon dioxide. Of course, a lack of proper circulation, filtration and sanitation may be the primary cause of the algae. The best process is one of elimination.

It requires work, effort and money to rid the water completely of algae. It is therefore best to use preventative chemicals and techniques, described later. Algae can cloud and color the water, making rescue attempts difficult and reducing depth perception of a diver. Algae itself is not harmful to swimmers, but pools with algae may also be harbor to pathogens like E-coli bacteria.

In addition to clogging up sanitation pathways in the water, algae also clogs up the pores in a filter, decreasing filter effectiveness and requiring more backwashing or medium replacement. Algae create a chlorine demand in the water for itself, actually consuming chlorine that should be working on other contaminants.

Cloudy swimming pool water is not safe to swim because the cloudiness could be caused by insufficient sanitizer, or unbalanced pool water, and extremely cloudy water makes visibility so obscured that diving and going underwater is unsafe. Rescuers potentially can’t see distressed swimmers underwater.

Proper balanced water which is safe for swimming requires 4 things:

  • Chemistry
  • Cleaning
  • Circulation
  • Filtration

Cloudy water can be caused by a deficiency in any one or multiple of these factors.

If in spite of having all 4 factors Chemicals, Cleaning, Circulation, and Filtration working together, the water is still cloudy then the problem is more complex and a good pool professional should be consulted.

One of the biggest and most overlooked problems in swimming pool care is biofilm. Biofilms form in all areas of a swimming pool, and contain almost 99% of the bacteria in the pool.

The biofilm will initially find a place to grow, and that can be in any or all parts of the swimming pool, not only on the pool walls, but also all through the filter and plumbing.

Once the biofilm has found a place to grow it begins colonization. This is where the bacteria begin to grow rapidly. Next comes protection, the biofilm will begin to excrete a protective coating that is resistant to most chemicals including chlorine and bromine. This coating is usually very slimy and heavy making it very hard for chemicals to penetrate and kill the bacteria at its core.

Once this protective coating is formed, the bacteria again undergo rapid growth. While chlorine and bromine will attack and kill the outer layers, the inner layers are still growing and multiplying. Once the biofilm has reached substantial size, it begins to break apart and again distribute itself all over your pool.

What's true for lakes is also true for swimming pools. Phosphate is a natural component of most swimmer wastes. It is also present in rain water. Phosphate is persistent and does not break down naturally. Landscaper's fertilizers, which may blow into the pool, have high phosphate content. For all of these reasons, pools can quickly build up high phosphate levels. This creates an abundant food source for all strains of algae and can make controlling their growth difficult.

When excess phosphate is present in a swimming pool, the symptoms often include the following:

  • Cloudy, Green Water
  • Slippery and Slimy Surfaces
  • Mustard and Green Colored Debris
  • Excessive Chemical Consumption
  • Poor Water Quality

The accumulation of oils and dirt from bathers is the biggest cause for waterline rings. It is important to using a pool liner cleaner which has been specifically designed for pools to clean it off. Household cleaners which are abrasive at times can actually dull the tiles or liner at the water tile, many products cause unsightly foaming in the pool and some can even react with the sanitizer.

One of the most common concerns with swimming pools is the presence of skin and eye irritations while swimming. Often this is a result of unbalanced water chemistry. By ensuring the water chemistry levels meet the recommended standards, skin and eye irritations can be treated and prevented.

Skin and eye irritation is most commonly the result of unbalanced water chemistry. When the pH is too low, the water is acidic and can cause skin and eye irritation. When the pH is too high, it can cause difficult to remove scale formation on pool surfaces and equipment. At first sign of skin and eye irritation, be sure to get a complete water test done including all parameters: Alkalinity, pH, Total Chlorine, Free Chlorine, Calcium Hardness, Total Dissolved Solids, and Cyanuric Acid (stabilizer or conditioner). If any of these are outside of the recommended range adjust as needed.

Maintaining chlorine residual is an important part of water chemistry in swimming pools, however, this may not be as easy as it sounds. One of the most common pool problems is excessive sanitizer loss, and this can be caused by a few things. The most common issue is low or no Cyanuric Acid.

Cyanuric Acid is designed to protect chlorine from being destroyed by sunlight. When chlorine is exposed to intense sunlight and UV rays it will degrade by at least 90% in just 2 hours. CYA is an important part of swimming pool water chemistry as it is designed to protect the chlorine. The more protection for the chlorine, the more protection for swimmers as the chlorine can then work to kill bacteria.

Dirt & debris in swimming pool water is an area of perennial concern. To keep the pool sparkling clean, the filtration system plays the most critical role and hence it is crucial that the filter be cared for and maintained consistently. A vital element in ensuring apt filtration is an effective filter gauge.

Every pool has a start-up pressure reading which is defined by the pool builder and differs from pool to pool. When this start-up pressure reading increases by 10lbs (4-5kgs) beyond the norm, it is referred to as High filter pressure. In case of the increase in pressure levels to this point, the solution is to backwash or have the filter cleaned.

Increase in start-up pressure is usually due to heavy non-living organic loading from contaminants such as sunscreen, lotions, hair products etc. A pool can never reach its maximum potential for water clarity until the filter is operating properly.

Naturally based enzyme products for treating swimming pool water help prevent high non-living organics from overloading in filters.