Explanations and Advice
The future of your pool depends on the company you hire today.
Swimming pools are one of a community's top amenities. Well maintained facilities require a lot of care and preventative repairs. For homeowners, a pool is probably the most expensive improvement on your property, besides the house of course. This section is to help you make more informed decision regarding pool improvements, construction and repairs. We've summarized the key components of swimming pools, common problems, solutions for repair, and the details that ensure longevity.
Typical Concrete Pool Construction
In ground concrete swimming pools are composed of a steel reinforced gunite or a shotcrete shell, capped horizontally with coping. The pool surface is typically marbelite plaster, a cement based coating sometimes referred to as a whitecoat or marcite. The waterline is finished with a perimeter band of tiles, commonly six inches tall.
The bond beam refers to the top section of the pool wall beneath the coping. This bond beam has additional steel reinforcement bars, often larger in diameter. The bond beam also increases in width (typically 10" to 12") for additional strength and surface area to attach coping. There is a caulked expansion joint between the coping and the pool deck.
The entire volume of water is circulated through a network of plumbing. The center of this circulation system is the pool pump, which draws the pool water in through skimmers at the water surface and bottom drains. The water returns to the pool through return fittings located either on the pool floor or walls.
Prior to returning to the swimming pool, the pool water is sent through a diatomaceous earth (DE), cartridge, or sand filter. A series of valves properly directs the water through the filters and isolates water flow through the filter and pump for maintenance. Finally, the filtered water is sanitized with the addition of an oxidizer, usually chlorine.
Swimming Pool Interior Surfaces
Pool shells are created with an incredibly strong concrete applied over a steel-reinforced cage. Because concrete is porous, the interior shell is coated with plaster to hold water, protect the structure and for aesthetics. Swimming pool plaster consists of a white cement and crushed limestone or marble dust aggregate. Quartz or pebbles can be utilized as an aggregate to increase durability and enhance the appearance. The white cement can be dyed to create a colored base as well. Darker colors will show streaks and stains more readily.
Common Problems with Plaster
Due to pool operation with chemicals and acid cleaning, the plaster finish can become coarse and thin, creating the need to resurface the pool. The plaster surface is like the "sacrificial lamb" of the pool. With proper care including proper water chemistry, the lifespan of the surface can be extended. Mistakes in the water chemistry and excessive use of acid for surface cleaning can diminish the useable life of the surface.
Resurface the pool and make sure that the contractor performs the maintenance necessary to properly cure the surface. Install a winter safety cover and balance the pool water in the off season. When draining and cleaning, use more pressure and less chemicals.
A note about "curing" and maintenance: Pool plaster cures under water. Freshly plastered pools should be filled as quickly as possible, without interruption. The first 14 - 28 days are the most critical and plaster continues to cure for up to a year. The water chemistry, maintenance and start up procedures are extremely important and should be followed based upon the type of plaster. Improper start up procedures, unbalanced water chemistry, and/or poor maintenance will result in surface staining and premature breakdown of the surface. Be sure the contractor that you have hired to apply the surface has a plan for curing. This is commonly overlooked, or improperly administered.
Coping and Tile
The top of the pool shell is finished with coping on the horizontal surface and tile on the vertical edges. Coping can be pre-cast cement, brick, or natural stones such as flagstone or travertine. Most coping has a rounded bull nose above the waterline. Perimeter tiles are normally frost-free ceramic or porcelain. Tiles create an aesthetically pleasing finish and provide a material at the surface that is non porous. The waterline where oil and scum accumulate needs to be routinely cleaned, the smooth tile surface makes it easier to maintain.
Common Problems with Coping and Tile
Cracked and/or loose coping and tile presents not only a needed repair issue, but also a potential safety hazard. Ceramic tile can be very sharp and when cracked or broken; the edges can cause cuts or skin abrasions. A loose coping stone could cause a swimmer to stumble or fall and become injured. In addition to these hazards, these conditions open the door for water loss and further damage to the surrounding areas, particularly in winter months.
A qualified pool contractor can perform an initial inspection and replace or reset stones and tiles as needed. The pool should be checked for hazards weekly at a minimum. If a significant percentage of the pool is in need of repair or replacement, it may be more cost effective in the long run to complete an entire perimeter replacement of the coping and tile. This is a very common swimming pool repair. Replace perimeter caulking whenever cracked, split, or separated.
Loose and/or cracked coping and tile could also be accompanied by beam damage. The concrete shell may deteriorate due to thermodynamic movement, freezing in winter or water damage. We have seen problems at the beam that started with too much sand in the mix when it was first built as well.
Caulking and Expansion Joints
A gap should be present between the perimeter coping stones and between concrete pads usually about 1/2". This gap, allows for the expansion and contraction of the deck in hot and cold temperatures. The gap will be established with a foam expansion material covered with caulking sealant to keep out water or a plastic hollow core manufactured material.
Common Problems with Caulking and Expansion Joints
You may have noticed that many of the solutions for problems outlined in the other sections include the replacement or repair of the caulking. The purpose of a caulk joint is to keep the area below dry in an effort to protect the pool, deck and other related components from freeze damage.
Replace perimeter caulking whenever cracked, split, or separated. Inspect below the caulk joint when exposed for proper clearance between decks and coping. Hire only experienced repair contractors, with a history of proper craftsmanship.
A Note about expansion joints during construction or repair:
Another common problem occurs during construction. The expansion joint is designed to be clear of any mortar or concrete to allow the needed room for expansion and contraction, which will occur with temperature changes. During the construction of pools the joint is not kept free of mortar or concrete. Once the scrap material hardens the necessary gap between the coping and the deck is compromised. In this condition, when the deck expands and contracts the coping and tile are broken free from the shell of the pool (bond beam). A concrete contractor that lacks experience with pools may not understand the importance of the expansion clearance required, particularly behind the coping. This condition has kept our construction crews busy with repairs for decades. It's that widespread of a problem.
Pool Plumbing Systems
There are code requirements for water recirculation in commercial pools. When built properly, the plumbing system is carefully engineered to ensure proper hydraulics including the flow rates, turnover rates and friction loss. The calculations used to design a plumbing system results in the information required for selection of the correctly sized pump. Dye testing confirms that the pool fittings are located in a pattern that is properly spaced.
Common Pool Plumbing Problems
Water loss and poor water quality are the two biggest issues. Not only does the makeup water present an additional expense, but the water loss also creates a potential for further damage to the structure, deck, and equipment. Water quality can suffer if the plumbing system was poorly designed, miscalculated or improperly installed.
If there is any significant observed water loss, contact a qualified contractor to evaluate the pool. Water loss is normal and will occur due to evaporation, wind, splash out, backwashing, and will be carried away with swimmers. Any amount greater than 1/2 to 3/4 inch per day should be investigated. Inspections of skimmer throats, tiles, grout lines and filtration equipment can rule out small leaks. The underground pool plumbing can be pressure tested to determine if there is a break in one of the lines.
Check for leaks at pipe penetrations. During construction or renovation, the seal between piping and the pool shell needs attention to detail. Creating a penetration through the shell during renovation is best done by core drilling and installing a proper seal. During new construction or other repairs, the piping and light niches should be packed tight with hydraulic cement. Draining the pool should not be performed without some caution. The entire pool could lift, or float out of the ground, due to hydrostatic ground pressure. This upward ground pressure is a factor when the swimming pool is drained, with enough pressure it could float the pool out of the ground like a boat in water. The pool should be equipped with a functional hydrostatic relief valve, to allow ground water to enter the pool and offset the upward lifting force with the weight of the water.
Filtration and Sanitation
A properly sized filter and sanitation system is required to remove impurities and suspended material from the pool water and to oxidize organics. Pool filters are diatomaceous earth (DE), sand, or cartridge. The filter media (the DE, sand, or cartridge) requires periodic cleaning depending on the size of the filter, type of media and variables such as bather load, landscaping and weather.
The sanitation of the pool water is accomplished with an injection of liquid chlorine via a peristaltic pump or restocking of dry chlorine products to an appropriate feeder. Salt systems have become more popular in recent years.
Common Problems with Filtration and Sanitation
Water clarity, dirt and/or sand passing back into the pool, and an insufficient flow rate are problems that can occur. Even with routine cleaning, the media typically requires periodic replacement prior to the replacement of the entire filter tank. Valves to control water flow may need replacement. A number of parts such as gauges, meters, and fittings require more frequent replacement, especially on the automated chlorinating systems.
Residential pool owners should learn to test water quality and learn basic system operation or hire a pool service. At commercial pools, staff should check all equipment daily and chemical levels hourly to ensure proper operation. If any deficiencies with equipment, chemical levels, or clarity are identified, swimming should be prohibited. Contact your pool professional immediately. Solicit and consider suggestions for preventative maintenance, repair, or replacement of equipment.
Salt Water Pools
Automatic chlorine generators have gained popularity over the last few years. High purity salt is added directly to the pool water to establish a salt level between 2800 and 3600PPM. This is below the threshold of what you can taste and it provides a soft, silky feel to the water. As filtered water with added salt passes through an electronic chlorine generator, electrolysis occurs. NaCl2 is separated in this process producing pure Cl2 (chlorine).
Winter Treatment & Safety Covers
Swimming pools are closed more often than they're open in the mid-Atlantic, for 6 to 9 months in many regions. This is not the time to ignore the pool. Water chemistry is equally important in the winter as in the summer. You need to protect your pool and plumbing systems during these months from the changing temperatures as well.
Swimming Pool Safety Covers are a great way to reduce liability and protect your investment.
Common Winter Problems
Pool water level too high or too low, water chemistry/clarity issues, pipe breaks, shifting concrete.
Contact a qualified pool professional to winterize the facility, treat water, and install a cover.