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Proper pre-conditioning of the swimming pool water after initial filling is essential for successful seasonal operation. Most authorities recommend that the pool be filled directly from the filler spout and not through the filter system. Many North Dakota waters contain large amounts of iron, manganese, and color, which must be removed prior to operation.

After the pool is filled, the water should be superchlorinated with a chlorine dosage of approximately 10 ppm. This will disinfect the water, satisfy the chlorine demand, and precipitate the iron and manganese. These precipitated materials can then be removed from the pool bottom by vacuum cleaning prior to start-up of the filtration equipment.

When the color or iron is not removed by the high initial chlorine dosage, coagulation with alum may be necessary.

6.2 POOL TEMPERATURE

The ideal water temperature for pools is a range of 76°F to 78°F. Temperatures over 80°F may lead to bathers’ discomfort and increase algae and bacterial growth. Swimming should not be permitted if the water temperature drops below 65°F.

Heating the pool water is desirable for swimming during cool weather. The pool heater should be thermostatically operated to prevent the pool water temperature from dropping below 65°F. This will permit raising pool temperatures to a comfortable swimming temperature in a shorter time. Problems commonly encountered in all water heaters are:

A. Rapid scale formation on the heating surface.

B. Severe corrosion on the waterside of the heating surface.

C. Condensation forming on the fire side of the heating surfaces results in deterioration of the boiler surfaces.

Softening of the pool water with zeolite type water softeners and/or the use of stabilizing agents such as polyphosphates may prove helpful. Care, however, should be taken that the pH of the water is adequately controlled so that a corrosive condition does not develop.

6.3 WIND PROTECTION

The use of windscreens or fences adds considerably to bather comfort during periods of inclement weather. Windscreens reduce the wind action and trap the solar heat, extending the time available for swimming activities.

Wind screens built of wood or fiberglass is effective, but reduces the spectator area. Portable screens of canvas or plastic are popular. These materials, when equipped with grommets, may be fastened to the barrier fence as needed.

6.4 POOL BOTTOM

The pool bottom should be kept free of visible sediment and dirt at all times. Two methods of cleaning in common use are brushes having long handles and suction cleaners. Brushes have the advantages of low cost and ease of use on small pools. In many cases, however, the combination of brushing and vacuum cleaning has worked the best.

Hairpins or other metal objects should not be allowed to remain on the pool bottom, as they will cause stains. A daily inspection should be made for these metal objects. They may be removed by hand, by brushing, or by the use of a magnet attached to a long pole.

6.5 SURFACE FILM

The pool surface should be kept free of floating film and debris. A hand skimmer should be available, consisting of a fine mesh net on an extension handle. Floating materials such as leaves or visible dirt should be skimmed routinely with this netting.

In those pools having an overflow gutter system discharging to waste, fresh water should be added at least once daily to the pool so that skimming action will take place for 10 to 15 minutes. This will eliminate much of the floating materials. Pools equipped with surface skimmers or overflow collection systems will have constant skimming action with re-circulation through the filtration system.

6.6 HARD WATER SCALE

When the swimming pool contains a hard, mineralized water, incrustation of the pumps, piping, heaters, and other appurtenances develop. This incrustation is composed primarily of compounds of calcium and magnesium. This precipitated material adheres to metal parts, forming a hard scale of calcium and/or magnesium carbonate.

One way of removing the undesirable calcium and magnesium is to run the pool water through a zeolite-type water softener. This has proved successful at many pools for treating the water used for filling the pool as well as the make up water. In addition, the zeolite softener may remove small amounts of iron in the solution.

Sequestering agents such as sodium hexametaphosphate may prove beneficial. These polyphosphate compounds tend to keep the calcium and magnesium carbonates in suspension, thus reducing their scale-forming action on metal surfaces. Some authorities recommend an initial dosage of about 2 oz. by weight of sodium hexametaphosphate to each 1,000 gallons of pool water, followed by a weekly addition of approximately 0.5 to 0.75 oz.

per 1,000 gallons of pool water.

Improper use of the calcium hypochlorite used for chlorination of the pool may be another source of scale in swimming pool waters. The directions for mixing of the hypochlorite solution should be carefully followed and care should be taken to keep the insoluble residue

(calcium carbonate) out of the pool. The use of the chlorine gas instead of calcium hypochlorite may prove beneficial in areas with scale-forming waters.

6.7 IRON REMOVAL

Many well waters contain iron in appreciable amounts, which will add color to the water and stain the pool. Make-up water containing iron should be added directly to the pool. When mixed with air and chlorine, the iron will precipitate and agglomerate into particles large enough to be caught on the surface of the filters. Best results are obtained when small increments of make-up water are added over a period of time rather than once daily.

6.8 ORGANIC COLOR

Many well waters contain organic color. When pools are filled directly with this colored water, the color may be so high as to prevent producing clear water. This color can sometimes be bleached by a high initial chlorine dosage. When chlorine does not remove the color, the re-circulation system should be started, bypassing the filters, and enough alum added to the water to provide a dosage of about 35 ppm. After the alum has dissolved and mixed with the pool water, broadcast an equal amount of soda ash on the surface of the pool.

Continue to operate the re-circulation system for an additional 2 hours, after which it should be shut down and the pool allowed to stand quiescent over night. By morning a heavy floc will be found on the bottom of the pool. Remove the settled floc with the vacuum cleaner before starting the filtration system. This type of treatment may also be highly effective for iron removal.

Be sure that the vacuum cleaner effluent is discharged to waste and not back to the pool through the inlets. This will result in remixing the settled floc with the pool water.

Alum is effective as a coagulant over a limited pH range. If the water is too acid, some of the alum remains in solution. When the water is too alkaline, the alum floc may tend to dissolve.

The efficiency of alum as a coagulant depends on the kind and amounts of dissolved minerals in the water supply. Hard waters coagulate quite readily over a fairly wide pH range.

The coagulation of very soft, highly alkaline, colored waters prevalent in western North Dakota may require careful adjustment of pH and the addition of a hardness element before proper coagulation and clarification can be accomplished. A hardness increase may be accomplished by the addition of lime (calcium carbonate) or calcium chloride. Calcium chloride will increase the hardness without increasing the alkalinity.

6.9 CLOUDY WATER

Occasional cloudiness of the swimming pool water occurs even when the filters and chlorination equipment are being operated in a proper manner. Cloudiness of the pool water may be due to many sources.

A. Cloudiness of the water in pools using diatomaceous earth filters may be due to filter aid passing directly into the pool water. Check the fabric covering the filter elements for holes or tears. If the fabric is in good condition, check to be sure that the proper grade of diatomaceous earth is being used.

B. Water may turn cloudy when soda ash is dumped directly into the pool. The addition of the soda ash causes a sudden rise in the pH of the water at the

C. Very soft, alkaline waters will remain turbid in spite of all efforts of the pool operator. This is due to the absence of calcium and magnesium in the water.

The total hardness of the water may have to be adjusted to at least 50 ppm to obtain adequate water clarity. The total hardness of the water may be increased without an increase in alkalinity by adding calcium chloride.

6.10 ALGAE CONTROL

Algae are microscopic plants that grow in water. The spores of algae are carried in the air and are deposited in a swimming pool during a wind storm, dust storm, or rain. In the water, algae spores grow, using carbon dioxide, nitrogen, and phosphorous and other available elements. When exposed to sunlight, these cells multiply at a very rapid rate. If the algae are allowed to grow, the pool will take on a disagreeable appearance and turbidity may increase to a point where the bottom is completely invisible, even at the shallow end of the pool. This high turbidity is a definite safety hazard to all persons using the pool facilities. Algae also tend to raise the pH of the pool water through the use of dissolved carbon dioxide.

There are countless species of algae, each with a different resistance to chlorine, but three main types are of concern to the pool operator:

A. Black algae are the most common and persistent variety. During the early stages of its growth, it will appear as small black (actually dark green) spots approximately ¼ inch in diameter. These spots will have a slippery finish and although seemingly fixed to the surface, they are easily removed. Simply brush them with a stainless steel brush and super-chlorinate to prevent further growth. Left to grow, they will increase in size and grip the pool walls tenaciously, actually growing into the wall. Advanced stages of black algae can be difficult to control and require repeated brushings and large doses of chlorine.

B. Green algae first appear as a green tint in the water, almost as if the entire pool has been dyed pale green. Individual plants cannot be seen. The onset of green algae can be very rapid, developing a full bloom in a matter of hours. It is easily destroyed by superchlorinating during the early stages of growth.

C. Mustard algae have a yellow-green color. It clings loosely to walls and steps.

A wave of a hand through mustard algae will usually disperse it.

Unfortunately, this will not destroy it, but only spread it to other areas of the

pool. Within hours, it will be back where it was previously removed. It is quite similar to the green algae and can be removed by the same method.

After treatment, the pool walls should be brushed with a stiff-bristled brush to remove the dead algae and expose any remaining living algae. If there are any stains left after brushing, they may be removed by light sanding with very fine waterproof sandpaper.

Chlorine is considered the best means of killing algae. Free chlorine is an excellent algaecide and if there is a constant, and adequate, free chlorine residual, 1.0 ppm or more, algae will not develop or grow. In pools where algae are already started, superchlorinating to about 10 ppm is usually effective.

In the past, copper sulfate has been used for alga control. Cooper sulfate has a number of disadvantages such as:

A. It is ineffective in water with high alkalinity.

B. It causes plugging of piping and distribution systems.

C. When used in excess, it can cause green staining of bathing suits and hair.

There are countless numbers of commercial products sold for alga removal. Many are effective for this purpose, but have little or no value as disinfectants. Do not use any algaecide that contains ammonia or mercury compounds.

Remember that free chlorine is an effective algaecide. If algae are present you must superchlorinate. It cannot be overemphasized that if proper levels of free chlorine are maintained, the pool will be free from alga problems.

6.11 INSECTS

Insects, particularly those that live around water, are attracted to swimming pools. The most common found in pools are Hemipteras or Cleopteras (beetles) which are predaceous insects and feed upon other insects in the pool area. They are not known disease carriers, but do bite or sting causing discomfort to the bathers.

Control of insects in and around the pool is difficult, as there are no known ways of permanently eliminating them. Superchlorination of the pool water will kill most of those in the pool and may drive the rest away. Most of the problem insects have wings, however, and will return as soon as the chlorine residual is back to normal.

6.12 PAINTING

One of the outstanding assets to any pool is clear, sparkling water. This is displayed to the best advantage by painting the walls and bottoms of the pool a light blue or white color.

Paint not only makes the water appear more invigorating but also, places a smooth coating on the concrete. An attractively painted pool is a safer pool because it is easier to keep clean and increases the underwater visibility. Underwater swimmers stand out clearly against light

One of the main reasons for painting, however, is for protection of the concrete against winter weather. Moisture can penetrate unprotected concrete. Alternate freezing and thawing within the pores will cause the concrete to spall off. In addition, tiny cracks will become enlarged and the exposed reinforcing rods will tend to rust and expand, damaging the concrete.

The most popular coatings for swimming pool use are cement base, rubber base, vinyl, and epoxy paints.

A. A cement base paint will give an acceptable finish at the least cost, but it is less durable than the more expensive paints. Generally, a cement base paint can be expected to last about one season.

B. Rubber base paints cost more, but they have an appearance and durability superior to the cement base paints.

C. Vinyl paints give superior finish and have a life expectancy of 1 to 2 years.

Vinyl requires a spray application and, more often than not, removes it from the do-it-yourself category.

D. Epoxy paints are expensive and difficult to apply, but they give a long lasting finish of high quality. A professional should apply epoxy paints.

The quality and durability of any paint application is substantially dependent upon the surface to which it is applied. Applying the best of pool paints over a loose and scaling surface will give disappointing results. Follow the directions supplied with the paint and pay particular attention to requirements regarding surface preparation.