Almost everyone has experienced the obnoxious chlorine odor and irritating red eyes of a poorly maintained indoor pool. Most assuredly, this is a sign of too much chlorine right?
Actually, there is not enough chlorine to preclude the continual buildup of those combined chlorine compounds we call chloramines.
As a result, water and air quality suffer, patrons are turned off and the pool is no longer an attraction for the facility. Worse, bacteria and viruses can infiltrate the water, while airborne viruses may spread in such an environment as well.
Most sanitation standards do not allow combined chlorine levels greater than 0.5 ppm. But typical test kits cannot distinguish the difference between free chlorine and total chlorine to determine combined chlorine above 3 ppm.
As the pool is used, free available chlorine shifts to combined chlorine. The pH levels also may increase, making the free chlorine less effective at killing pathogens. Water quality then deteriorates, affecting air quality as well.
Salt chlorine generators are one solution for these water and air quality issues. We know that water is a conductor of electricity, but not a very good one. With salt chlorine generators, sodium chloride (NaCl), is added directly to the pool (most systems operate between 2,500 to 4,000 ppm) to increase the conductivity and provide a chemical base from which chlorine is generated.
The salt solution is passed through an electrolytic cell housed in the plumbing, where it is broken down to chlorine gas (the most powerful form of chlorine) and sodium hydroxide. Chloramine compounds passing through the energized salt cell are, for the most part, destroyed, ultimately resulting in greatly improved air quality.
Because the chlorine gas is saturated in the chamber’s water, it quickly converts to pure sodium hypochlorite (with a low pH value) and sodium hydroxide (at a high pH value), which balances the pH to near-neutral. This process requires fewer balance chemicals than thetrichlors, dichlors, cal hypos and sodium hypochlorites. The pure chlorine effectively kills the bacteria and viruses and virtually eliminates combined chlorine.
After the chlorine conversion, the product of the resulting chemical reaction reverts back to salt, ready to generate more chlorine once again. The salt-to-chlorine-to-salt cycle is regenerative, so there’s no need to replenish bulky chemical storage tanks and feeders. Maintenance on chlorine feed pumps, injection fittings and tubes is eliminated.
Only a small amount of salt is lost through filter backwashing, splashout and drag-out, so only occasional, small additions of salt are needed to compensate.
Properly maintained pools do not contribute to air quality issues. Minimizing combined chlorine, especially during high bather usage, is the key. There may be some air quality issues due to the number of people around the pool, but that can be controlled with proper air ventilation.
While salt chlorine generators are not the only solution for indoor air quality issues, they can provide a direct and immediate impact. Regardless of the system, however, pool water quality must be combined with proper operation and maintenance routines, accurate water testing, and basic common sense. If it looks and smells bad, something’s definitely wrong. If it looks too good to be true, test it first.
Finally, remember that too much chlorine can do just as much harm as too little.