Using enzymes to reduce chlorine demand
By R.T.Coffey, Ph.D.
Recent assessments have indicated that in swimming pools, 65% of avoidable chlorine losses arise from inefficient treatment of the organic debris that is present in virtually all pools. While some chlorine losses are unavoidable (due to UV from sunlight, bathers and chemistry involving cyanurate stabilizer), nearly all pools suffer much higher rate of chlorine loss than necessary.
Remedying this accelerated chlorine loss is now quite simple due to better understanding of the underlying causes and the development of highstrength enzyme products. Chlorine’s primary function is to disinfect water to keep bathers safe from waterborne bacteria and viruses. Chlorine is also well known to be a powerful oxidizer that can break down non-pathogenic contaminants.
The role of organic debris in driving up chlorine demand is one of the most broadly occurring challenges in recreational water. Organic debris is overwhelmingly the most common type of contaminant that chlorine oxidizes in pools, and it comes at a high price. When chlorine in water attacks any organic molecule or amine, it breaks a single chemical bond within the target molecule. The chlorine decomposes in the reaction, no longer available to disinfect or oxidize anything. Each 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 as well as to inorganic amines, and that chlorine needs to be replaced to maintain disinfection levels.
The newer enzyme products are impressively effective because they so efficiently eliminate the very thing that costs pools so much chlorine: 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 energyproducing biochemistry in humans, enters recreational water via urine.
The best enzyme products contain a broad spectrum of enzyme types to deal with the vast array of organic materials that show up in pool 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. And this is a crucial advantage of 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 chlorine only operates once.
Enzyme products are the fastest growing category of chemical products used in recreational water. They are simple to use; they’re just added to circulating pool water on a regular schedule, typically weekly or, for a large, heavily-used facility, daily. A good enzyme product will destroy haze and yield crystalclear water. Being natural materials, enzymes are non-toxic. 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 an enzyme product in the worst available pool water and judge for yourself. It usually takes no more than two weeks to see real benefits. The chlorine savings, the reduced maintenance, and the impressive improvements in water quality have been convincing many more pool pros to use enzyme products each season.
Dr. Rick Coffey 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.