Enzymes and phosphate-reducing products have been used in the pool and spa industry for a number of years. Claims on how effective these are have taken on a life of their own. While the products can be tremendously helpful to pool owners and service people, they do have limits. This article will discuss what these products are, what they are capable of and what they cannot do. Information on how they can best be used to help pool operators will also be covered.
Phosphate reducers are specialty chemicals used to remove phosphates from pool water. They are typically salts of aluminum or lanthanum which, when added to water, produce insoluble phosphate compounds which are removed through filtration, vacuuming or both.
It should be noted that not all phosphates found in pools are bad. Some phosphates (polyphosphates) and other phosphorus-containing compounds are excellent sequestering agents, protecting the pool from metal staining and scale. Some phosphates (namely orthophosphates) are known to be a source of food for algae. Phosphate reducers were introduced as a means of limiting this food source; thus curtailing the ability of algae to grow in the pool. However, since these products are not EPA registered as algaecides their labels cannot claim algae control. Nevertheless, many believe that these products will kill algae.
Removing phosphates reduces or eliminates the need to maintain proper sanitizer residual. This is simply not true. A proper sanitizer residual must be maintained in the pool at all times and in all areas of the pool to ensure proper disinfection. As an added benefit, maintaining this residual and shock treating regularly will also prevent algae from becoming a problem no matter what phosphate level exists.
Removing phosphates eliminates the need to use an algaecide. Since removing phosphates from pool water does not kill algae, an algaecide is still recommended. Maintaining your sanitizer residual and using an algaecide regularly will prevent any unexpected algal blooms from occurring.
Removing phosphates will kill algae. If this were true, then the products could make algaecidal claims on their label. Algae can store phosphates in their cells, enabling them to survive periods of time in the absence of phosphates. As some of these cells die, their phosphates can be used by the surviving algae as a nutrient source.
Phosphates create a chlorine demand on pool water. This is false. Phosphates are already at their ideal oxidation level so chlorine does not react with them. For this reason, phosphates do not create a chlorine demand. The two are simply unrelated.
Once phosphates are removed from a swimming pool, they will not come back. Phosphates are common in the environment and are constantly being introduced into the pool from a variety of sources including swimmers, leaves, bugs and other water treatment products. As a matter of fact, phosphonate-based sequestering agents are some of the best products available for providing protection against metal stains and scale. These phosphates are not orthophosphates and are not useful to algae as a food source. It should be noted that orthophosphates themselves are not useful as sequestrants.
Despite the limitations, phosphate reducers can still be an effective tool for managing pools if used as part of a routine maintenance program. Since phosphates are so common in the pool, phosphate levels must be monitored diligently to ensure that they remain low. This will ensure that any problems that do arise may be minimized. Also, when choosing a sequestering agent, the pool operator will have to decide whether the benefits of using a phosphate reducer outweigh the benefits of using a phosphorus-based sequestering agent to prevent metal staining and scale (typically polyphosphates are used, not the orthophosphates that feed algae).
Enzymes are specialty chemicals that are used to help eliminate or reduce the severity of waterline scum lines or their severity, improve sanitizer efficiency by reducing organic loading and reduce filter cleaning. Enzymes are proteins produced by biological processes that act as catalysts to speed up reactions by lowering the energy level required for that reaction to occur. Enzymes are selective in nature, with specific enzymes acting with different types of products. For example, an enzyme that will catalyze the breakdown of an oil molecule will likely have little effect on a protein or starch.
The use of enzymes in the pool has several effects. For starters, by breaking down oils and other complex molecules found in pools, the amount of material available to form scum lines at the water’s edge can be greatly reduced. Additionally, since enzymes help break down some very complex molecules in the water, oxidizing sanitizers such as chlorine and bromine are more effective at breaking down those contaminants, then become more available for their intended use of killing bacteria. Another benefit is that by breaking down these large complex products, filters will be less likely to get fouled, resulting in longer runs between cleanings. Since chlorine will destroy enzyme activity over time, their activity time in the pool is limited. For this reason, they do need to be used as part of a regular maintenance program in order to maintain the benefit.
Enzymes are living organisms. This is not true. Enzymes are produced by living things but they themselves are not alive. This means that they cannot be killed. Instead, their ability to help catalyze reactions can be destroyed (through high heat, chemical incompatibilities, etc.).
Synthetic enzymes. There is some confusion in the industry with terms like synthetic versus natural enzymes. Enzymes by their very nature are produced by natural things and are therefore themselves natural. Synthetic enzymes are substances which are not enzymes yet mimic their activity. Since they are not actually enzymes, they cannot be labeled as such and none are known to be used in the pool and spa industry.
All enzymes are alike. Broad spectrum enzymes are products that contain a wide range of enzymes and enzyme activities. Other products contain selected or targeted enzymes which mean that proteins are selected to target particular types of contaminants that need to be broken down. Products containing selected enzymes can also be broad spectrum in that they are blends of selected enzymes and broad-spectrum enzyme products may not necessarily target the desired contaminants. For this reason, it is important to know what type of enzyme product you are using to achieve the desired result.
Enzymes will break down all contaminants. Enzymes will not destroy all contaminants in the water. Enzymes will only act upon substances to which they can bind and because of this only certain contaminants will be acted upon, depending upon the types of enzymes that are present.
Enzymes and phosphate reducers are specialty products that can be used to help maintain water clarity and pool aesthetics. While each type of product has benefits and limitations, if the proper products are chosen and used as part of a regular maintenance program, they can be effective tools for managing a pool or spa.
Weber is manager of quality and technical Services with Arch Chemicals, now a part of Lonza. A 16-year industry veteran, he’s also a consultant for APSP‘s Recreational Water Quality Committee.
Enzymes are proteins that act as catalysts, speeding up chemical reactions. The substance on which the enzyme is reacting is called a substrate, which fits neatly into an enzyme. The enzyme weakens the bond in the substrate, facilitating the reaction.