Curing Indoor Pool Water Problems

Indoor pools are often pretty stunning. In northern climates, they are quite the attraction in hotels & condominiums & apartment buildings. They provide year round enjoyment for millions of people around the world as they vacation or just go about daily living. Indoor pools provide terrific places for low-impact and “zero gravity exercise” for healthy individuals as well as those who may need physical therapy. You’ll find them in many towns and cities across the country. Schools, community centers, are busy with swimmers twelve months each year. Indoor pools are not just for the rich!

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. This article will help you to understand those needs.

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.

Water balance is the single most often misunderstood problem of pool care and how great a difference it makes. When water balance is incorrect, nothing works right chemically: chlorine or sanitizer efficiency is affected, the water can become cloudy, the water can become irritating to skin, hair & eyes, the water smells, etc.

Briefly, high pH and total alkalinity lead to “slow” and inefficient chlorine and sanitizer activity. Algae & bacteria growth is promoted leading to cloudy water. Some eye irritation and a sometimes “slimy” feel. Low pH and total alkalinity lead to “too fast moving” chlorine or sanitizer; the water may be very clear but has a strong odor as well as an acidic “feel”. Chlorine is more rapidly used up and exhausted.

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.

A similar situation exists with spas & hot tubs where insulating covers trap heat, but also when not removed for extended periods of time (several hours per week), odors and chloramines, bromines & other unwanted odors accumulate.

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.

Oxidation also occurs via direct sunlight. UV light is an excellent oxidizer. The more direct sunlight you can get on the pool, the better. This is one the real problem areas with indoor pools; there’s just no sunlight on the pool for 5 or more hours each day. Direct sunlight can dramatically cut down on the amount of water mold and even algae (notice that most of these problems typically start in “shady” areas of the pool).

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 and 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 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 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. Automatic covers are a different story. They are almost impossible to remove and clean, although the same build-ups occur and affect the water. When you have dealt with cloudy water or algae in an indoor pool that has a blanket or automatic cover, there is 90% or higher probability that the problem started with the cover being dirty or having a bio-film.

Bio-films are just that (see our other articles dealing directly with bio-films) a film of bio-matter or bacteria growing on a surface. What is a surface? In the pool a surface is the walls and floor of the pool, the ladder or rails (both inside and outside of the rail), underneath the treads, light lenses, behind the light in the niche, the back side of the skimmer flap (weir), directional returns (eyeballs), safety ropes and floats, pool toys, etc. I think you understand.

Bio-films 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 bio-film will grow. To remove bio-films in the not so obvious areas, use products such as AquaFinesse or sphagnum moss products such as PoolNaturally; these products will remove the bio-film and then prevent it from returning. Reports are coming back to us showing that regular use removes bio-films 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.



. by Ronald Parrs