Like all things in modern life, fresh, clean water in our pools, spas and spraygrounds is a given. But, did you ever stop for a moment and wonder, how did we get here?
In case you haven’t, here’s a quick primer.
The first “pool” showed up sometime in the third millennium (that’s B.C.) in the form of a “great bath.” It was constructed in Mohnejo-Daro, a site on the border of ancient India and Pakistan, near a large river. To form this first “great bath,” the locals redirected the river to flow into and out of a gouged-out rocky area each day. The natural in-out flow of the water cleansed the pool, keeping it safe for whoever was allowed to use it. (Do you think they sold memberships?)
Later, the Greeks and Romans advanced the business of artificial swimming pool construction when they added ducts designed to circulate and, hopefully, clean the water. Later still, around 1837, the indoor pool showed up in the form of six facilities (complete with diving boards) in London.
But it wasn’t until the 1896 Olympic Games that swimming became a fashionable sport, one suitable for the masses. Spurred by the games, pool construction increased, spawning elite clubs (the Oxford Swim Club opened its doors in 1906) and luxury above-ground pools (businessmen in Philadelphia even built an ocean-liner, aptly named Olympic, which came complete with the world’s first floating, above-ground pool).
With all of this pool construction came the very real need for robust water-cleansing systems that worked effectively, efficiently and economically to maintain safe pool and recreational water.
At some point, two lines of thought emerged. One used natural features to fill and cleanse recreational water. So-called natural swimming ponds (also known as natural swimming pools) are the result.
These pools use Nature’s purifying properties of plants (and a small, man-made filter to extract debris, such as leaves) to purify the pool. In practice, the pool water circulates sufficiently through the plant area, where surplus nutrients, impurities and bacteria are transformed by the plant material and other natural water organisms, eliminating the need for chemicals (or constant cleaning).
Though we’re most familiar with so-called traditional artificial pools (Olympic swimming pools, above-ground pools, in-ground pools, etc.), it is possible to build and safely use natural pools.
According to Michael Littlewood, Landscape Designer from the U.K., natural pools present an ecologically diverse (and often less expensive) pool than the more conventional above-ground pool. The advantage to the natural pool, besides its self-cleaning mechanism, is that it provides patrons with a clean, safe place to swim and the wildlife with an appropriate, clean habitat.
But, it is not very good for a competition swim meet and it can only be used during warm weather, which is what led to the explosion of the pool we know and love today. It’s also what led to the development of effective water treatment programs.
As we all know, just because the water in your pool is clear, it doesn’t mean it’s clean. Low levels of bacteria, viruses and pathogens can exist and can lead to a variety of maladies, including diarrhea and skin-, ear- or upper-respiratory infections. The paths to avoiding these little buggers are many and varied. Here are a few:
Just Add Salt
Sometimes called saltwater pools, this process uses an electrical cell and salt to generate chlorine on-site. Proponents of this method claim the advantages of the salt method include:
* Smoother water (easier on skin and eyes)
* Lower operating costs
* Safer (no need to handle or store dangerous chemicals)
The disadvantages to this system are the higher up-front costs to cover the initial loading of the pool.
Designed to use copper and silver to destroy bacteria and algae without the use of chemicals, ionizing systems circulate pool water through ionization cells that emit a low electrical current that reacts with the metals in the water and purifies it.
The advantage of this system is generally considered the relative lack of chemicals involved, which means your staff has to handle and store fewer hazardous chemicals. The common disadvantage of is the cost, which is typically higher than either saltwater- or standard chlorine disinfection.
Ultraviolet (UV) Sterilization
UV sterilization is another way to disinfect as water circulates through a pipe and is sterilized by UV light instead of chemicals. UV sterilization does not inhibit algae and does not break down dissolved nitrogenous nutrients that are responsible for algae growth, so you still need to use some type of oxidizing sanitizer. While not as expensive as ionizing systems, cost can be an issue. The advantage is, again, less chemical usage/storage.
Standard Chlorine Disinfectant
In the standard chlorine disinfectant procedure, chlorine is fed into the pool water. Chlorination kills the harmful microorganisms that cause ear-, eye- or upper-respiratory infections and acts as a rapid and persistent sanitizer, which is effective in killing off algaecides and other contaminants.
Since this by far is the most common method, here are some things to consider for your pool:
* A strong chlorine smell is not an indication of too much chlorine; it is a red flag indicating a super dose of chlorine is needed--typically called “shock treatment.” The additional dose destroys organic contaminants and oxidizes ammonia while the nitrogen compounds rid the pool of irritating chloramines odor.
* Another term for shock treatment is “superchlorination.” In this situation five or more chlorine products are added to the pool water. This is used to rid the pool of algae and bacteria that might be hiding in filters or hard-to-sanitize areas.
* Other disinfectants are used, such as bromine and ozone. These can be generated on site by passing an electrical current through the pool water itself. It is important to maintain a safe concentration of disinfectant.
Standard Chlorine, Best Practices
The most important thing to remember is to keep the water pH in a range of 7.2 to 7.6. Anything higher will reduce the sanitizing power of chlorine, while a lower pH will cause eye discomfort to the swimmer. As a rule, non-chlorine sanitizers are less harsh, but anything overused will result in side effects.
How Much Of What?
Test your water regularly and work to maintain these tolerances:
* Free chlorine--1.0-4.0 ppm
* Combined chlorine--none
* PH--7.2 to 7.8 (ideal range is 7.4-7.6)
* Total alkalinity for liquid chlorine, cal hypo, lithium hypo—80-100 ppm
* Total alkalinity for gas chlorine, dichlor, trichlor and bromine compounds—100-120 ppm
* Total dissolved solids--not to exceed 1,500 at pool startup
* Calcium hardness--200-400 ppm
* Cynauric acid--30-50 ppm
As a general rule, you should:
* Store chemicals in a dry, cool and shaded area.
* Remember to read all manufacturers’ instructions carefully.
* Never mix different types of chlorine or other chemicals together--they should be added separately.
* Avoid breathing in any fumes or vapors when using chemicals.
* Don’t buy more pool chemicals than needed for one season--they lose effectiveness over time.
* Make sure all chemicals are inaccessible to children.
* Save on chemical costs by adding chlorine for a shock treatment after dark; use during the day will be lost to sunlight (outdoor pools).
In general, a well-managed pool will be without smell or taste, and the water will be crystal clear.
Helen Downey is a freelance writer in Medina, Ohio. She can be reached via e-mail at firstname.lastname@example.org
* Woodhouse Waterscape. URL: www.garden-landscape.com