Pool Biz Lingo
By Buzz Robinson
Owning a swimming pool or spa has many benefits-providing recreation for the family, quiet times with loved ones and the enjoyment of a backyard oasis. New owners are often at a disadvantage when it comes to understanding how the pool operates or the terminology used by pool professionals. This explanation and glossary will help current and potential pool owners comprehend the professional lingo relating to mechanical and maintenance systems. Many local pool retailers of these establishments also hold 'pool schools' to help new swimming pool and spa owners understand what is involved in care and maintenance. By maintaining proper circulation, filtration and chemical balance, backyard swimming pools and spas will be easy to maintain and a joy to have.
Pump & Water Supply
The central hub of a pool is the pool pump, a pump-and-motor assembly, which circulates the water in the pool. It's designed to take all of the water in the pool and run it through the filter at least once a day. The time it takes to do so is the turnover rate. Residential swimming pools are generally designed to have a 6- to 8-hour turnover rate. At the front of the pump is a pump strainer basket, which prevents solid debris from entering and clogging the pump.
Water is supplied to the pump by the skimmer, the main drain and, if present and being used, a dedicated wall vacuum fitting. The skimmer is located at the top edge of the pool and has a bobbing plastic door, called a weir or weir door, that traps any floating debris in the skimmer. The debris is captured in the skimmer basket, located underneath the skimmer deck lid. The skimmer is also where a vacuum hose or automatic pool cleaner hose can be connected to clean the bottom of the pool.
The main drains - usually split for safety purposes - are located at the bottom of the pool. They have main drain grates, covering open pipes plumbed to the pump. The main drain grates should always have antivortex covers. Antivortex grates are upraised and solid on top so that the water pulls through the sides; this prevents the formation of a dangerous vortex.
The main drains don't function like bathtub drains, but simply provide water to the pump from the bottom of the pool. It is imperative that the main drain grates be properly attached with screws. If the grate breaks or comes loose, the pool should not be used until the grate is replaced.
Some pools have a dedicated wall vacuum fitting to which a vacuum hose or automatic cleaner hose can be attached. A safety vacuum lock is a spring-loaded cover used for safety purposes.
Suction vs. Pressure Side
A pool has two sides pertaining to its equipment: the pressure side and the suction side. The main drain, skimmer and wall vacuum fitting are suction lines, as they are located on the suction side of the pump, which sucks water from the pool and carries it to the pump. The pressure side or return side pertains to all of the water sent back to the pool after the water has passed through the pump, the filter and the heater.
Suction-side pool cleaners use a segmented vacuum hose and attach to either the dedicated vacuum fitting or the skimmer to power them around the pool, while pressure-side cleaners attach to a dedicated pressure line and are supplied water at high velocity by a booster pump.
Filters
When the pool pump runs, it pulls water from the skimmer, main drain or the wall vacuum fitting. The water then is pushed through the pool filter to remove fine debris, such as sand and organic material. Once the water goes through the filter, it ends up on the pressure side of the system and returns to the pool. There are three types of pool filters: sand, cartridge and DE:
• A sand filter uses silica sand or sand-like matter to filter the water. The water enters through the top of the filter, trickles down through the sand and flows back to the pool. In the bottom of the sand filter, a series of laterals or plastic slotted fingers hold back the sand and allow only the water to return to the pool.
• A cartridge filter uses a pleated cartridge to filter the water. An increase in the pressure indicates that the cartridge needs to be cleaned. The cartridge is taken out of the tank, hosed off thoroughly and replaced. Next to the pressure gauge on top of the filter is the air relief valve, which can be opened once the pump is turned on to expel any trapped air in the system.
• A DE filter has grids on the inside of the filter tank. The grids are coated with DE (diatomaceous earth), a fine white powder that is actually micro-skeletal plankton. A measured amount of DE, determined by the square feet of surface area of the filter, is added through the skimmer after each filter cleaning.
Backwashing
Both sand and DE filters are cleaned by backwashing, which runs the water through the filter backwards. This process allows the debris trapped within the filter to be removed and run out of the filter tank through a pipe called the waste line. A multiport valve is commonly used to backwash the filter. The pressure gauge on top of the filter determines when the filter needs cleaning. As the filter traps more dirt and debris, the pressure reading on the gauge will increase and the flow of water back to the pool will decrease. When the pressure rises 10 pounds past normal operating pressure, it is time to backwash.
Water Maintenance
Pool and spa water must be chemically balanced and sanitized to keep it clear and free of harmful germs and bacteria, and must be treated to keep it from becoming either corrosive or scale-forming. Corrosive water can etch the finish of a plaster pool, corrode metal components and allow the finish to become more prone to staining. Scale-forming water will deposit calcium over the entire finish of the pool, causing discoloration and roughness.
Water balance involves maintaining a proper pH, total alkalinity and total hardness.
• The pH (potential of hydrogen) is a measure of acidity or alkalinity, using a scale of 0 - 14 with 7.0 being neutral; pH above 7.0 is more alkaline, and pH below 7.0 is more acidic. The pH range should be 7.2 to 7.8, ideally 7.4 to 7.6. When the pH level is too high, scale formation and eye irritation can occur; muriatic (hydrochloric) acid is used to lower it. If the pH is too low, water becomes corrosive.
• The total alkalinity is the amount of alkali materials in the water necessary to maintain a stable and balanced pH. The proper range is 0 - 100 ppm when using unstabilized chlorine, and 100 - 120 ppm when using stabilized chlorine, chlorine gas or bromine as your sanitizer. Sodium bicarbonate or baking soda raises the total alkalinity and pH.
• The total hardness is the amount of dissolved calcium and magnesium in the pool water; its proper range is 200 - 400 ppm.
To protect chlorine from the UV rays of the sun, stabilizer or cyanuric acid is used; it should range from 25 - 50 ppm and be added in bulk once or twice per year. Low stabilizer levels allow the chlorine to be depleted quickly on sunny days. Some types of chlorine have small amounts of stabilizer mixed in to help replenish what would be lost through splash-out or backwashing.
Sanitizers, Oxidizers & Balancing Chemicals
Chlorine is often used to help keep the water safe and clean. It is both a sanitizer and an oxidizer. A sanitizer kills germs and an oxidizer burns out organic material. Free available chlorine, or residual chlorine, is the chlorine that is available to kill incoming algae and bacteria; it should be kept between 1.0 and 3.0 ppm. Combined chlorine is chlorine that has already been used and has formed a chloramine. Chloramines do not attack new bacteria, and they create a heavy chlorine smell and irritate the eyes, nose and throat. Shocking the pool or achieving breakpoint chlorination burns out all of the chloramines in the water and leaves the desired residual chlorine.
Chlorine can be released into the water through a chlorinator or erosion feeder. A floating chlorinator holds slow-dissolving chlorine tablets and is placed into the water. An erosion feeder also uses slow-dissolving tablets but plumbs in-line with the pool equipment. It has a control valve to increase or decrease the amount of chlorine entering the pool. A salt chlorine generator, often used in salt water pools, utilizes a power pack, electrolytic cell and common salt to actually produce the chlorine, eliminating the need to buy, store and handle it.
Other types of sanitizers include bromine, mineral sanitizers and biguanides.
• Bromine is sold in tablet form and often used in hot tubs/spas because it is not affected by heat or sunlight to the extent that chlorine is. It requires periodic shocking with a powered oxidizer, such as monopersulfate (MPS).
• Mineral sanitizers use trace amounts of silver and/or copper to sanitize pool or spa water. While they still require an oxidizer, such as chlorine or MPS, they significantly reduce the amount of oxidizer needed.
• Biguanides are hydrogen peroxide-based sanitizers that reduce the surface tension of water, creating a silky feel. While more expensive than other sanitizers, biguanides are not affected by heat or sunlight so their levels remain relatively stable.
Ozone generators or ozonators are devices that produce ozone, a powerful oxidizing agent. They must be used with small amounts of a traditional sanitizer since ozone does not maintain a residual.
Balancing Chemicals
Other common chemicals used in swimming pools and spas are balancing chemicals for the pH, total alkalinity and total hardness. They include sodium bicarbonate, soda ash, muriatic acid and calcium chloride.
• Algicides assist in destroying algae and can be used in maintenance doses to help prevent algae growth during hot months.
• Clarifying agents help clear turbid water quickly by drawing all of the particles together so the filter can pull them out easily.