While both pools and spas require chemical additives to sanitize and condition the water, there is a big difference between cold water and hot water chemistry. In many cases the chemicals used are the same, but in some instances they are radically different. Never use pool chemicals in a spa without first making sure they are compatible with hot water!

Like pool water, when a spa is filled with your garden hose it is generally chlorinated and fluoridated. But left untreated, water is a perfect host for all kinds of living organisms and mold. Spa water, because it is kept at a high temperature, is particularly susceptible to organic growth. The most important chemical your spa needs is some form of sanitizer to kill bacteria. There are several different types of sanitizers available, which we all cover shortly. Some of the other chemicals you may need are listed below:

OXIDIZER/SHOCK: Used to burn off organic waste, kill algae (uncommon in spas), and to keep the water clear.

PH ADJUSTERS: Used to raise or lower the pH, which is a measurement of how acidic or basic the water is. Normal pH should be between 7.2 and 7.8 (the pH of the human eye is around 7.5). At this range sanitizers work better, scaling and corrosion is reduced, and skin and eye irritation is avoided.

TOTAL ALKALINITY ADJUSTERS: When alkalinity is correct, it helps maintain proper pH levels.

ALGAECIDE: Used to prevent algae, or to kill algae when used with shock. Algae is usually not a problem in spas, but occasionally occurs in summer months when spa temperatures are kept lower.

CLARIFIER: Clears up cloudy water.

SEQUESTERING AGENTS: Used to remove metal from the water, preventing discoloration or staining. Primarily needed when well water is used to fill the spa.

There are primarily two standard sanitizers and couple of new, ãalternativeä sanitizers used in spas.

Chlorine: While there are several types of chlorine that may be used in swimming pools, the only kind compatible with hot water is di-chlorine, or di-chlor for short. It is available in granular form specifically packaged for spas, and is also sold for pools. Use approximately 1.5 oz. per 500 gallons of water weekly.

Di-chlor levels should be maintained at between 1 and 3 ppm (parts per million). At 1 ppm the water is sanitary. It may be cloudy or discolored, but it is safe. Keeping the level closer to 3 ppm will allow longer time between testing, as well as helping to keep the water clear and sparkling. At low levels, chlorine combines with ammonia (which is produced by sweat, urine, or other methods), to form chloramines (also called combined chlorine). It is the chloramines that cause skin and eye irritation and unpleasant odors. ãShockingä the spa will remove chloramines, as well as burning off any organic materials like dead skin cells, etc..

Bromine: Similar to chlorine, bromine has two advantages. When it combines with ammonia to form bromamines, it still sanitizes. The second advantage is that bromamines do not irritate skin and eyes like chloramines do. Like chlorine, bromine should be maintained at a level of 1 to 3 ppm. All procedures used with chlorine, like shocking, balancing pH, etc. apply equally to bromine.

Alternative Sanitizers: In recent years, highly sophisticated compounds have been developed that combine the performance of several different spa chemicals, as well as prolonging their effects, while at the same time reducing or eliminating many of the undesirable qualities of chlorine or bromine. One of these new sanitizers is biguanide, best known by the brand name Baquacil. Chemically, biquanides are a long chain polymer the should be kept at a level of 30 to 50 ppm. Biguanides have the advantage of not being affected by heat or light, so they maintain a more consistent level which requires less testing and longer times between applications. They are odorless, do not form compounds with ammonia, and are generally hypo-allergenic. The greatest disadvantage to their use is cost, and the fact that only biguanide compatible shock and algaecide can be used. A second generation alternative to chlorine and bromine is a product called EZ Spa. EZ Spa is a combination of compounds that function together to create a total water conditioning system. In dry form, EZ Spa is a consumer friendly product that can be handled safely. When exposed to water, a chemical reaction creates a very strong and long lasting oxidizer to kill bacteria and burn off organic wastes. It also contains a dry acid that adjusts pH, along with a flocking agent that causes small particles to coagulate and collect in the filter. Together they form a one powder, once a week product that is odorless, hypo-allergenic and effective.

In addition to the above mentioned chemical sanitizers, there are two additional products designed to sanitize spa water. The first is an electronic purifier called an ozonator. Basically a device that bombards the spa water with ultra-violet light as it passes through the plumbing, breaking the water molecules down which then briefly recombine as ozone, a naturally occurring gas that kills bacteria and burns off organic wastes. Use of an ozonator reduces chemical requirements by up to 70%. WE HIGHLY RECOMMEND THE INCLUSION OF OZONATORS WITH ALL SPAS.

The second product is called the Nature² system, which is a tubular plastic container that is inserted into the filter. Lasting approximately 4 months (at a cost of around $30), the Nature² releases trace amounts of silver and zinc ions into the water, which prohibits the growth of bacteria. When used in concert with an ozonator, chemical requirements drops to virtually zero. Note that I said virtually. Some retailers make claims that theirs is a zero chemical spa. There is no such thing as a chemical free spa! While chemical requirements can be reduced to as little as a teaspoon of di-chlor per week, they cannot be eliminated completely. Please note that silver prevents bromine from functioning correctly, it should not be used together with the Nature² system.