Sunday, October 26, 2014

Swimming Pool - How to Clean and Test Pool Water

Algae are a very large and diverse group of eukaryotic organisms. Most are phototrophic. Given them right conditions, they can grow very fast in most marine environment including swimming pools. To maintain a healthy swimming pool, the main task is to control their growth—the best process is elimination.

In this article, we will examine how to clean and test pool water to eliminate algae.

Algae Problem

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, phosphates, and/or carbon dioxide. Of course, a lack of proper circulation, filtration and sanitation may be the primary cause of the algae.

There are over 21,000 known varieties of algae! In the pool business, they avoid all of the complication by referring to algae by the colors:[1]
  • Green Algae
    • They are frequently found free floating in the water, although they also cling to the walls.
    • They reduce water clarity and are thereby distinguished from severe copper precipitation, which will impart a clear, green color to the water. 
    • Varieties of green algae also appear as "spots" on surfaces, particularly rough areas, or places where circulation is low. 
    • They also show up as "sheets", where large wall sections, or even the entire pool, is coated in green slime.
  • Yellow Algae (aka Mustard Algae)
    • A wall clinging variety which is usually found on the shady side of the pool.
    • They are sheet forming, and can be difficult to eradicate completely—re-infection is common. 
    • This variety is resistant to normal chlorine levels and must be dealt with diligently. 
  • Black Algae
    • They are perhaps the most aggravating strain of algae, they can be extremely difficult to eradicate completely.
      • Their roots extend into the plaster or tile grout, and unless the roots are destroyed completely, a new head will grow back in the same place. 
      • Their heads also contain protective layers to keep cell destroying chemicals from entering the organism.
      • Like yellow algae, black strains can bloom even in the presence of normal sanitizing levels and proper filtration. 
  • Pink Algae
    • They are not really an algae at all, but a form of bacteria. 
    • They appear as spots or streaks in corners and crevices. 
    • They are slow to spread and rare for them to bloom over an entire pool.

How to Test Pool Water?

For simple tests such as pH test and total chlorine (or bromine) test, you can use a test kit like:
  • Taylor K-1000
It is a decent test agent and simple to use.  Or you can bring pool water in a container and go to companies such as Leslie's Pool for their free testing service.  Their water analysis report typically include the following test categories:
  • Free Available Chlorine
  • Total Available Chlorine
  • Cyanuric Acid
  • Total Alkalinity
  • pH
  • Acid Demand
  • Copper
  • Iron
  • Total Dissolved Solids
  • Phosphates
These companies also recommend remedies for your pool based on the test results.

How to Clean Pool Water?

There are two cleaning mechanisms in your pool system:
  • Chemical 
  • Mechanical
We will cover those two cleaning mechanisms in our next posts.  Stay tuned.

Photo Credit


  1. Algae (
  2. How to Open Your Swimming Pool and Balance Pool Chemicals 
  3. How to Maintain A Swimming Pool - Clean and Test Pool Water
  4. How to Close a Swimming Pool - Clean and Cover a Pool
  5. Why don’t we winterize pools in the Dallas area?
  6. PBS Pool Products - Commercial (Skimmer)
  7. Chlor Neutralizer
    • Reduces the chlorine or bromine levels in pools and spas
    • 2.5 oz. per 10,000 gal.
  8. How-To: Know the Size of Your Swimming Pool (Travel to Wellness)
  9. Your Disinfection Team: Chlorine & pH 
  10. Leslie's Dry Acid Buckets - Leslie's Swimming Pool Supplies
  11. Chlorine in Pool Water and Nearby Plants
    • If the pool or spa water has a high chlorine content, uncover it and allow the chlorine to dissipate before using the water for irrigating the landscape. Or, chemically remove the chlorine by adding solium thiosulfate of sodium sulfite to the water.

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