inPERSPECTIVE / AQUATICS: Improve Water Quality, Solve Chemical Supply Problems

March 1, 2022

Enzymes are the fastest-growing category of chemical products used in recreational water. The better-quality versions eliminate a variety of problems that are commonly encountered in managing water quality and maintaining water contact surfaces. At the same time, enzyme products significantly reduce chlorine demand. And these products are safe and readily available.

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Enzyme products are impressively effective because they eliminate the very thing that causes so many problems in recreational water: organic debris.

Organic debris is material in water that has a biological origin. Insects and plant matter that fall into the water become organic debris. Dead algae become organic debris, as do hair, dead skin cells and other bits shed by bathers. All humans, including adults and often without realizing it, leak urine into recreational water. Similarly, creatinine, a byproduct of energy-producing biochemistry in humans, enters recreational water via urine.

In many cases, the biological origin of organic debris is not so obvious. Materials derived from plants, for example, are used in the production and formulation of many everyday products that we use. Examples include skincare, lotions and hair care products from bathers, and beverages spilled into pools.

Organic molecules in nature tend to range in size from large to enormous. In chlorinated water, chlorine begins to break them down. These reactions produce molecules that are still quite large, but many are small enough to pass through filter media unmolested and remain dissolved in water. Organic debris tends to accumulate in recreational water because of its long life in the water along with daily additions. Organic debris plays different roles among these observed problems, which has helped obscure its role as a prevalent troublemaker.

Phosphate is well-recognized as a critical nutrient for algae growth and reproduction. But algae also need organic material as nutrients that they can convert into algae cell components. Organic debris in the pool water provides most of the nutrition that algae could hope for, and phosphate usually accompanies organic matter into the water.

Organic debris often contributes considerably to hazy water. The haze results from particulates large enough to scatter light. Short filter-cycles (the need to clean filters more often than we'd expect) are usually caused by the portion of organic debris that is large enough to be trapped via conventional filtration.

Waterline scum buildup is another problem caused by organic debris. When we encounter these rock-hard deposits, the tenacious glue that holds that scale together is organic debris.

The role of organic debris in driving up chlorine demand has been, perhaps, one of the least recognized but most broadly occurring challenges in recreational water. Chlorine's primary function is to disinfect water to keep bathers safe from water-borne bacteria and viruses.

It's well-known that chlorine also has a reputation as an oxidizer that can break down contaminants in water. Organic debris is, by far, the most common type of contaminant that chlorine oxidizes in pools. This is a convenient secondary benefit to using chlorine, but it comes at a high price.

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When a chlorine molecule (hypochlorous acid) attacks an organic molecule, it breaks a single chemical bond within the organic molecule. The chlorine molecule decomposes; it is no longer available to disinfect or oxidize anything. As mentioned before, the molecules in pool water delivered by organic debris are quite large. Each such organic molecule contains many chemical bonds, which can easily number in the thousands. So, a lot of chlorine gets sacrificed to reaction with organic molecules, and that chlorine needs to be replaced to maintain disinfection levels. A realistic figure is that at least 65% of the avoidable chlorine demand in recreational water is caused by organic debris.

Enzyme product manufacturers select enzymes that they believe will be effective at chopping up the kinds of organic molecules we find in recreational water. The best products contain a broad spectrum of enzyme types to deal with the vast array of organic materials that show up in recreational water and are also robust enough to resist rapid destruction by chlorine. These enzymes chop up organics into tiny bits, even down to fragments just two-carbon atoms in size.

This is a crucial advantage to using enzymes rather than chlorine to rid water of organic debris: A single enzyme molecule can operate on organic debris tens of thousands of times, while a chlorine molecule only operates once. Although enzymes are not oxidizers, they are massively efficient at breaking down organic debris. In fact, they are so effective that the tiny breakdown products can leave the water by off-gassing directly into the air; this reduces odors. Since organic contaminants don't become aggregated to filterable size, the burden on the filter is reduced. The organic debris already collected on a filter is also decomposed by a good enzyme cocktail; enzymes clean filters, so you don't have to.

In terms of water quality problems, it should now be apparent why enzyme product use is growing so rapidly. Enzyme products are simple to use; they're just added to circulating pool water on a regular schedule. A good enzyme product will destroy haze and yield crystal-clear water. Enzymes eliminate one of the major sources of chlorine demand, they lengthen filter cycles and they reduce odors. And enzymes destroy the glue that binds waterline scum into a hard mass.

Enzymes are maintenance products. Even the most robust enzymes will eventually succumb to chlorine attack, so they need to be replenished, typically weekly. It usually takes a couple of weeks to see impressive benefits. Because they are so efficient, dosages, and therefore costs for weekly use, are very modest. And given the labor time saved plus the reduced uses of chlorine, acid and other products often used to deal with the same sets of issues, enzyme products are often a bargain.

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Because of their growing popularity, and because most of the sources of organic debris are also the sources of phosphates in pool water, a few manufacturers offer combination products: enzymes plus phosphate remover. This combination is about as convenient as it gets for simple, reliable pool water maintenance, high-quality water and algae prevention.

Being natural materials, enzymes are nontoxic. Some of the best enzyme products are NSF/ANSI 60-certified. There is no reliable test for determining the power of one enzyme product versus another. The best approach is to simply try a product in the worst available recreational water and judge for yourself. For this reason, sample material for trials is often available from reputable manufacturers. Most recreational water professionals who have tried enzyme products have liked what they've seen and so the category continues to grow. RM

 

ABOUT THE AUTHOR

Rick Coffey, Ph.D., is general manager for Lo-Chlor LLC, a manufacturer and marketer of specialty pool chemical products for recreational water. He holds a Ph.D. in Physical Chemistry as well as a B.S. in Marine Biology. For more information, visit lo-chlor.com.

 

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R.T. Coffey | Ph.D.