What Is the Shelf Life of Liquid Algaecide?

What Is Algae?

• Michigan State University explains: "Algae are a group of aquatic organisms containing chlorophyll, a green pigment, that enables them to produce food from water, air and sunlight by a process known as photosynthesis." The most commonly seen algae in swimming pools are the floating green kind. However, algae aren't always green even though they are full of chlorophyll.
  Treating the algae depends on the type of algae you have. For example, floating algae might succumb to liquid algaecide added to your pool's water; yellow and black algae may need to have the algaecide applied directly to your pool's surfaces. Yellow and black algae are also common in swimming pools, and these algae attaches themselves to the surfaces of your pool, rather than floating on top of the pool's water.

What Causes Algae?

• Algae are a traveling host, so to speak. They can be introduced into your pool's water by the wind, rain, foreign debris and your swimsuits. Algae can also begin to grow and thrive in your pool if the water you used to originally fill the recreational gem initially contained algae spores. While this slimy single-celled organism won't make you sick like bacteria can, it can cause other problems in your swimming pool and its surrounding area.

Algae Concerns

• Algae are slippery, and when they affix themselves in and on your pool, they create a slip-and-slide surface that might cause falls and injury. Algae give your pool a dirty look, and with good reason. Algae tax your pool's chlorine supply, reduce pesticide effectiveness and clog your filter. Naturally, your water turns cloudy and looks dirty, tastes and smells funny and can even make you itchy when you swim in it.

Shelf Life of Liquid Algaecide

• Algaecide is a mixture of components designed to kill the algae in your swimming pool. When Joe S. Wilker, Sr., applied for his patent on January, 3, 2000, for his composition of algaecide, he explained, "Most algaecidal agents are formulated and marketed as liquids; however, such liquid formulations have certain undesirable disadvantages, notwithstanding their overall effectiveness in eradicating algae. For example, liquid algaecidal agents comprising sodium hypochlorite have limited shelf lives generally ranging from six to eight months." A liquid algaecide left over from last swimming season would be past its shelf life.

Algaecide Considerations

• Wilker suggests that you use an algaecide primarily made up of alkali hydroxides; the EPA also notes that many algaecides contain alkyl ammonium chlorides. These chemicals are different from sodium hypochlorite. Wilker also recommends that swimming pool owners use a powdered algaecide rather than a liquid algaecide, stating it is safer to ship, distribute and use, more effective in treating swimming pool algae and holds an "indefinite shelf life," as the mixture does not activate until it is met with water.
  Your best bet for determining the shelf life of the particular algaecide you use or are desiring to purchase is to read the manufacturer's label. Each algaecide is made up of different agents, so shelf life varies. Read your label to determine the shelf life of your brand of algaecide. Contact the manufacturer directly if that information is not included on the product label, and always discard of expired algaecide per the environmental recommendations of your resident county and the EPA.