There is unfortunately a ton of information or as I would put it, misinformation about many pool & spa topics, and these need to be cleaned up and truths be told.
Let me clear up some myths, legends & misinformation about:
An Indoor swimming pool is often pretty stunning. They provide year round enjoyment for millions of people around the world as they vacation or just go about daily living. Indoor inground pools provide terrific places for low-impact and "zero gravity exercise" for healthy individuals as well as those who may need physical therapy.
More importantly, indoor pools require special treating. Yes, they are swimming pools. Yes, they have the same type of filtration systems that outdoor pools have. But there are differences in the care that is required. I'm here to help you understand those needs. These same issues are true of indoor swim spas (sometimes known as "endless pools").
There are 4 main concerns of indoor pools that need to be addressed: Odors, Oxidation, Bather Load, and General Care.
Indoor Pool Odors. Who hasn't walked into a hotel or building and there is that immediate "pool chlorine" odor? You KNOW that the facility has a swimming pool! The question is why? Why does it have to be that noticeable? Many people wonder and question - sometimes rightfully so - how well the pool is being cared for. Indoor pools should not "smell." Will they have an odor? Yes, but they should not smell.
If a pool smells - especially if the odor is acrid or pungent - you can be sure that something in the pool is not right. And if your eyes become irritated, the situation could be even worse. Keep in mind that the problem is NOT the chlorine. The problem is the water balance. In cases of pools having attached spas, chemicals and bather wastes are aerosolized and spewed into the surrounding air.
A further problem is the continual formation of chloramines or combined chlorines or bromines. These form when there is excess waste like nitrogen. Sanitizer efficiency is severely reduced and a pungent "chlorine" odor is emitted. Chlorine "odor" is fine. Think of a bathroom or sick room that has been cleaned with chlorine (bleach). The odor left behind tells you that it is CLEAN. That's the chlorine odor we want. This leads us to the question of Oxidation.
Oxidation. The bottom line is indoor pools need to be shocked as often as, if not more often than, outdoor pools. In the oxidation process (shocking or super chlorinating), unfiltered or not filterable waste (greases, body oils, body powders, perfume, nitrogen) are oxidized (burned off) are released into the atmosphere or surrounding air. But the pool is indoors. What happens then? That's exactly the point.
Many of those "gassed-off" wastes can't fully gas off. What essentially happens is that these wastes literally hit the ceiling and fall back down into the water. The problem is made worse in cases of poor ventilation. Ventilation can be in the form of fans, open doors & windows, ventilation systems, whatever it takes to change the air and bring in fresh.
Even in the middle of winter it is a very wise idea to do a monthly super shock (2 to 3 times the normal amount of chlorine or shock), remove the solar blanket or automatic cover, open the windows and let all of that stuff just get out of the house.
Bather Load. Bather load is exactly that: how many people are using the pool at a time. Obviously, hotels, condominiums and other commercially operated pools have greater use. The more people using the pool, the more stuff is being put in (as mentioned above). The more a pool is used the better from a circulation & even from a "cleaning" (feet & bodies rubbing & touching the pool surfaces) point of view.
In commercial pools, shocking may need to be done 2 to 4 times each week to break up swimmer waste, chloramines and other stuff. This is especially necessary after large events with above average swimming use.
Similarly in residential pools, even above ground pools, even though the bather load is less, it still must be shocked. Weekly at least. Do not put the solar blanket or automatic cover back on for at least 3 to 5 hours to allow proper gassing off the oxidized waste.
General Maintenance. A little more care in maintenance is needed with indoor pools. Why? Three general of reasons: lack of sun, year round use, perception that "it's indoors, nothing's getting there."
We've already looked at the lack of sun. Regular oxidizing of the pool is paramount.
Year round use is just that. The pool is available 24/7 wherever you are. The filter needs to operate 8 to 12 hours each day. Period. With that in mind, the pool needs good, regular cleaning. That means weekly vacuuming of the pool interior. If you don't feel vacuuming is necessary, then at a minimum brush the pool walls and bottom weekly. Brushing aids in breaking up biofilms, algae, water mold (even though you may not see these problems).
No matter what type of filter your pool utilizes - sand, cartridge or DE - be sure to chemically clean the filter every 3 months with a good filter cleaner. Backwashing of sand or DE filters and rinsing of cartridge filters only removes excess dirt and debris; it will not remove filtered greases, oils, and body wastes. Filter chemical cleaners break up these accumulations. Here's the analogy: would you rinse dirty clothes or launder them with detergent?
Solar blankets and automatic pool covers need regular cleaning. Solar blankets should be removed and chemically cleaned (for the same reasons that you chemically clean a filter) at least twice each year.
Biofilms are the breeding ground that can later develop into algae, pool mold (white water mold), or pink slime. If there is a surface and it becomes wet or moist, a biofilm will grow. To remove biofilms in the not so obvious areas, use AquaFinesse. AquaFinesse and ActuvNzyme will remove the bio-film and further prevent it from returning. Reports are coming back to us showing that regular use removes biofilms even on the underside of solar blankets and automatic pool covers.
Enjoy your pool & treat it right. You'll have much less work to do.
For almost all of my career in the swimming pool & spa industry, I've heard of people being "allergic" to chlorine. I hate to burst everyone's bubble, but there's really no such thing.
In the first place, Chlorine (Cl) is an element. Chlorine is an integral part of so many products that we all touch and use every single day at home, school and work. Chlorine is in plastics, certain finishes, bleach (obviously). Chlorine is one of the most excellent and economical products ever found to kill harmful bacteria and control algae blooms.
What we do see are "sensitivities" to chlorine. And frankly, it's not necessarily chlorine, but chloramines (chlorine combined with nitrogen which are smelly & very irritating). In a swimming pool, when you have high (sometimes even any chloramines) concentrations of chloramines (over 1.0 ppm) plus a pH level that is out of balance, you're almost guaranteed to cause reactions in various people manifesting as skin rashes, eye irritation, bad odors and so on.
As bacteria builds up in the swimming pool water, but especially on pool surfaces where biofilms flourish, swimmers make direct contact with this bacteria and become infected. It's really that simple.
We typically see these problems who don't shock their pool regularly or don't maintain a proper level of chlorine and then aren't maintaining a proper water balance.
There is tremendous hype regarding Ozone & Ozonators being used in swimming pools for the purpose of "eliminating" chlorine. Like it or not, that's a fallacy.
In the first place, Ozone (O3) is NOT a primary sanitizer. Primary sanitizers are chlorine (in the typical forms of Cal Hypo, sodium hypochlorite - bleach, sodium dichloro - fast dissolving granules, trichloro - slow dissolving granules or tablets or sticks), bromine (typically a tablet, sometimes a granular blended with sodium dichloro), biguanides (PHMB such as Soft Swim or Baquacil). These products can last for hours or days in normal swimming pool water killing bacteria and algae. Swimming pools, spas & hot tubs must use a sanitizer to continuously kill bacteria and algae.
Sanitizers can be oxidizers, but oxidizers can't be sanitizers. I know it sounds like semantics, but sanitizers are meant to stay working in the water for "long" periods of time (hours or days as opposed to minutes).
Second, although Ozone is an excellent & powerful oxidizer, Ozone is very unstable and has a normal half-life of less than 30 minutes. The three atom Ozone molecule rapidly breaks down into its normal Oxygen state after it comes into contact with anything. Like other good oxidizing products, it goes in, gets its work done, then gasses off.
Another problem with Ozone is that it can't be stored. and Ozonators can't produce a significant amount of Ozone. As mentioned, Ozone gasses off quickly. It would take days and in reality weeks to completely ozonate a typical residential swimming pool. In contrast, you can completely chlorinate that same pool in a matter of minutes.
One of the "pros" of ozone aside from it being an excellent oxidizer, is that it smells "nice" when it's working. Have you ever smelled the air after a thunder storm? What you smell is Ozone. The electricity in the air "charges" the oxygen (O2) and converts it to Ozone. Keep in mind that like so many things that we like, Ozone is a potent poison. It works in the pool plumbing lines killing whatever bacteria it can while there, but once it's in the body of the pool, it will rapidly dissipate and gas off. In other words, if the bacteria is on the far end of the pool, away from the return jets that allow that final small amount of Ozone in the pool, you haven't accomplished anything because the Ozone will have gassed off long before reaching the bacteria. Furthermore, certain bacteria or viruses or parasites such as Giardia or Cryptosporidia are almost completely unaffected by Ozone.
In summary, although Ozone generators (ozonators) have a good purpose (picking up the slack of additional oxidation), Ozone still needs to be completely backed up by a primary sanitizer.
The first fact to understand about Ultra Violet - UV - in treating water swimming pools, spas & hot tubs is that UV DOES NOT KILL ANYTHING! Period.
When treating pool water or spa water, UV-C is used. UV-C is a kind of radiation. Radiation breaks down the RNA and the DNA of the bacteria or parasites as it (the bacteria or parasites) passes through the UV light in the UV generator.
UV light is produced in a generator and is sent in a clear quartz tube inside of the generator. As the pool water or spa water flows around the tube, the UV light being emitted comes into contact with the bacteria a "scrambles" the RNA & DNA of the microbe, rendering it unable to reproduce.
As we mentioned in the First Key to Great Pool Care & the First Key to Great Spa Care, it takes many turnovers of the water to fully filter through the system. In swimming pools you would need to run your pool 24 hours daily to "ALL" of the water to be filtered ONE time per day. Spas & hot tubs obviously require less time due to their smaller capacity.
That's all well & good, but considering that somewhere between 95% and 99% of all bacteria is NOT floating, because it's on or in the biofilm found on all of the pool or spa surfaces, UV is only able to "treat" 1% to 5% of the bacteria or microbes present.
That's the singular best reason why treating bacteria, algae, microbes, parasites, etc must be a multifaceted approach. In other words, you still must use some type of "primary sanitizer" to properly treat your pool or spa water - chlorine; algaecides prevent algae growth; shock treatments or oxidizers oxidizer swimmer & environmental waste; enzymes breakdown organic waste, greases & oils; borates further help buffer the water balance; biofilm removers "slough off" the biofilm that harbors the non-planctonic bacteria.
One final thing to keep in mind: the tube emitting the UV light will eventually cloud or occlude (through biofilm and/or scale build-up) thereby lessening the amount of UV light able to "treat" the microbes it's supposed to treat.
In large commercial or public swimming pool applications, UV is a truly good part of overall sanitation, but for the average pool or spa owner, the payback more than likely isn't there.