Swimming Pool Maintenance
More Than Simply Adding Sanitizer, Adjusting the PH and Running a Filter
Proper chemical treatment is necessary to prevent problems such as mineral scale and metal stain formation, cloudy water, or deterioration of the interior finish and the equipment.
EFFECTS OF BAD WATER CHEMISTRY
Five factors affect water quality: pH, total alkalinity (adjusted to carbonate alkalinity), calcium hardness, total dissolved solids, and sanitizer. Temperature is also a factor that impacts water chemistry balance, but in most cases is not considered a controllable factor.
The pH, carbonate alkalinity, calcium hardness, total dissolved solids, and temperature of the water, are used to determine the overall water balance. Properly adjusting these parameters allows you to keep the water balanced, in order to avoid the tendency of the water to become either “scale forming” or “corrosive/aggressive.”
Scale-forming tendencies are usually related to high pH, or elevated levels of alkalinity, calcium hardness, total dissolved solids, or a combination of these. Conversely, corrosive/aggressive deterioration is usually related to low pH, or low levels of carbonate alkalinity, calcium hardness, total dissolved solids, or a combination of these. .
Corrosive/aggressive water can also destroy pool tile grout, metal light rings, heaters, and pool equipment.
- ! Low Carbonate Alkalinity
- ! Low ORP Readings
- ! Sanitizer Issues
- ! Scaling or Staining Issues
- ! Filtration Issues
- ! Degradation of the Interior Finish
- ! Algae Growth
Maintaining proper service and proper water balance (chemical levels or ‘ranges’) is essential in the prevention of these issues. Water chemistry should be maintained in accordance with APSP ‘Balanced Conditions’. The following parameters are recommended:
pH should be kept within the range of 7.2 – 7.8. At a pH below 7.2, the water is considered to be ‘aggressive’, and a pH above 7.8 is considered to be ‘scaling’, and has the tendency to precipitate minerals and/or metal causing scaling or staining of the surface.
Carbonate Alkalinity should be kept within the range of 80 – 120 ppm. To Adjust Alkalinity: Increase: 1.5 pounds of Alkalinity Increaser or Sodium Bicarbonate will increase the total alkalinity of 10,000 gallons of pool water by 10 ppm. Decrease: Add small amounts of liquid or dry acid (diluted or dissolved) once each day until desired level is reached. In general, about 2 pounds of dry acid will reduce total alkalinity of 10,000 gallons of pool water by 10 ppm. For minor adjustments, do not add more than one pound of dry or one pint of liquid to 10,000 gallons of water per day. Remember, do not add ANY acid if pH is less than 7.2.To reduce total alkalinity, add small amounts of acid, either liquid or dry (dissolved in a bucket of water), over a period of several days instead of making significant adjustments rapidly.
Calcium Hardness content should be kept within the range of 200 – 400 ppm . A low calcium hardness level can cause the deterioration of the interior finish and tile grout. To increase calcium hardness, add calcium chloride. One pound of calcium chloride will increase the calcium hardness of 10,000 gallons of water by 10 ppm.
Total Dissolved Solids should not exceed 1500 ppm (above the source water TDS). If higher than 1500 ppm, the water has the tendency to precipitate minerals and/or metal causing scaling or staining of the surface For salt water pools, the TDS should not exceed 1500 ppm above the source water TDS plus the added salt. The water can also become cloudy. It is recommended to drain some of the water and replace with fresh water. Alternatively, in certain regions of draught or water restrictions, there are methods to reduce or remove metals, minerals, and dissolved solids through filtration.
Cyanuric Acid should be kept within the range of 30 – 50 ppm. It is recommended to periodically drain some of the water and replace with fresh water, so that cyanuric acid levels do not build up.
- ✔ Test Water Regulary
- ✔ Invest in filtration system
CHEMICAL FACTORS OF POOL OPERATION
Proper chemical treatment is essential in order to prevent potential problems such as mineral scale and metal stain formation, cloudy water, or deterioration of the interior finish and the equipment.
Five factors affect water quality: pH, total alkalinity (adjusted as carbonate alkalinity), hardness (as calcium), total dissolved solids and sanitizer.
The pH, total alkalinity, and calcium hardness, as well as the temperature of the water, are used to determine the overall water balance. Water balance is the tendency of the water to be either “scale forming” or “corrosive/aggressive.” If you water has scale-forming tendencies this is usually related to high pH, high total alkalinity, and elevated calcium level (hard water) or a combination. Corrosive or aggressive water is commonly the exact opposite of the chemical factors involved in scale forming. This can destroy pool walls and cause corrosion of equipment.
To prevent these problems, it is essential to maintain proper chemical levels or values in the pool water.
pH refers to the level of activity of an acid or base in the water and is the most critical chemical factor in swimming pools It is measured on a scale from 0-14 with 7 being neutral. If you have a pH value between 0-7, this is considered acidic. A pH value of 7-14 is considered alkaline with 14 being the greatest base activity. Your pool water is best kept in the range of 7.2-7.8. If below 7.2 the water is considered to be corrosive and a pH higher than 7.8 will increase the tendency for cloudy water. Changes in the pH are caused by many factors, but the most common is the sanitizer used. Standardly chlorine is used in pools, and it comes in a variety of forms. For example, most tableted forms of chlorine have a very low pH and will tend to lower pH over time, while liquid chlorine is very high in pH and will tend to raise pH values. A quality professional can work with you in understanding what types of sanitizer are best for your pool.
Total alkalinity is the ability of your pool water to resist a change in pH. The purpose is to help manage or control the pH in the pool. Total alkalinity acts as a buffer so when materials are added to a pool that would cause the pH to go up or down; the changes are controlled in order to prevent damages to your pool water balance. Remember that total alkalinity is best within the range of 80-120 ppm. When less than 80 ppm the water is considered aggressive, and the pH can quickly increase or decrease. If higher than 120 ppm, the water can become cloudy and scale forming with the pH increasing. To reduce total alkalinity, add small amounts of acid, either liquid or dry, over a period of several days instead of making significant adjustments rapidly.
To Adjust Alkalinity:
Increase: 1.5 pounds of Alkalinity Increaser or Sodium Bicarbonate will increase the total alkalinity of 10,000 gallons of pool water by 10 ppm. TO
Decrease: Add small amounts of liquid or dry acid once each day until desired level is reached. In general, about 2 pounds of dry acid will reduce total alkalinity of 10,000 gallons of pool water by 10 ppm. For minor adjustments, do not add more than one pound of dry or one pint of liquid to 10,000 gallons of water per day. Remember, do not add ANY acid if pH is less than 7.2.
Calcium hardness refers to the sum of all the calcium dissolved in water. Having very high levels of calcium can be unstable and even more unstable if the pH or the total alkalinity rise above the normal levels. This can result in cloudy water and/or scale. Soft or low calcium water is considered aggressive and can remove calcium from plaster. If the pool is vinyl or fiberglass, the low calcium water may attack metal fittings and heat exchangers. This attack can result in the destruction of the fittings or pinhole leaks in the heater. When corrosion occurs, stains to appear on pool surfaces. Calcium content is best in the range of 200-400 ppm.
How to increase calcium hardness:
To increase calcium hardness, add calcium chloride. One pound of calcium chloride will increase the calcium hardness of 10,000 gallons of water by 10 ppm.
Total Dissolved Solids
Total dissolved solids (TDS), is a lesser issue in fresh water, but pool water that has not been replaced over time, can accumulate TDS. TDS is essentially the sum of all materials dissolved in the water and normally run in the range of 250 ppm and higher. In general, when the TDS exceeds approximately 1500 ppm, problems may begin to occur. TDS can result in cloudy or hazy water at an elevated level. Therefore, it can be difficult in maintaining water balance, the reduction in sanitizer activity, and foaming. To reduce TDS, you need to drain some of the water and replace with fresh water. Unfortunately, sequestering agents do not help when high TDS levels are causing cloudy pool water.
EFFECTS OF CYANURIC ACID
When maintaining pools, cyanuric acid (CYA) is a key ingredient for pool maintenance and allows your pool to remain chlorinated in direct sunlight and will keep chlorine active in your pool. Without CYA, the chlorine will quickly dissipate and leave your pool unprotected.
While, CYA provides many benefits for the pool industry and the typical pool owner, having high levels of CYA can also cause damage and cause the chlorine to be less effective. CYA needs to be regularly diluted with fresh water, and if not, CYA can rise to high, unwanted levels, beyond the standard 30-50 ppm.
Having an increase in CYA can cause a number of chemistry problems such as skewed alkalinity readings, low ORP readings, and inefficient chlorine. In addition, having large quantities of CYA can cause damage to plaster which is why it’s essential to understand the effects and consistently monitor CYA levels.
Adjusting Total Alkalinity to Carbonate Alkalinity
When high CYA is present, a significant portion of the CYA affects the total alkalinity readings. This must be adjusted for, when using the saturation index to determine water balance. This is done by subtracting approximately 1/3 of the CYA (in ppm) from the total alkalinity (in ppm), to arrive at the carbonate alkalinity.
If this adjustment to the carbonate alkalinity is not made, and instead, the total alkalinity measurement is used, the water will be in a more corrosive condition than the saturation index calculation states. In other words, it will give you a false indication that the water is balanced, when in fact, the water is in a corrosive condition.
CONSCIENTIOUS CARE TIP #1 (FILTRATION)
Filtration refers to the mechanical cleaning of pool water. It is commonly overlooked, but is a very important part of properly maintaining a pool. The filtration system removes the particulate matter, consisting of the dirt and debris that cause the water to be hazy or cloudy. A filter plays an important role of removing the algae that the sanitizer has destroyed as well as much of algae’s food source. A fully functioning filter will help keep the water clear, allowing for the continuous use of your pool.
Conscientious Care Tip #2 (Circulation & Turnover)
Water circulation is the process of regularly moving pool water through the pump and filtration system. It is recommended that all the pool water should be ‘turned over’ once a day. ‘Turn over’ is described as the time it takes for the volume of a pool’s water to pass through the pump one time. For example, if your pool has an eight-hour turnover time, it means that when the pump is running, it will take eight hours for the entire volume of water (or equivalent gallonage) of your pool to move through the pump and filtration system. This ensures the majority of the body of water gets filtered, and that the sanitizer or any chemical additions are distributed throughout the water.
To ensure for optimal circulation of the water, it is recommended that at least 2/3 of the water be drawn from the main drain at the bottom of the pool (or from the automated vacuum system) and approximately 1/3 be drawn from the skimmer(s) to remove debris on the surface of the water before it settles out.
Furthermore, the water flow should be in a circular pattern around the pool. This is done by adjusting the water return fittings (typically, in a clockwise flow) so that all of the returns are circulating in the same direction. Aiming the return fitting slightly downward can often improve the water circulation and flow. This helps to ensure that debris on the surface is removed by the skimmers prior to settling to the bottom of the pool.
THERE ARE THREE COMMON FILTER TYPES: SAND, DIATMACEOUS EARTH (DE), AND CARTRIDGE
Sand filters utilize sand as the filtering medium. As water flows through the sand, the dirt becomes trapped. The sand is cleaned by periodically backwashing (reversing the water flow), which removes the collected dirt and debris. Sand is a good filtering media because it is inert. It does not react with pool water or pool chemicals, and will last many years before the sand needs to be replaced.
Cartridge filters are pleated fabric arranged within a rigid cylinder. As the water passes through the cartridge(s), the fibers trap dirt and oils. Cartridge filters are not as efficient as DE filters, but are used in many residential pool applications because of the ease of cleaning, and replacing of filters if damaged or old. Cartridge filters require more frequent cleaning to remove dirt, debris, and oils that build up.
Diatomaceous Earth (DE) Filters consist of a fine mesh fabric that is coated with a layer of fine white diatomaceous earth powder. In turn, the fine diatomaceous earth powder is capable of filtering out extremely small particulate matter from the water. DE filters are the best of the three filter types, in terms of filtration of fine particulate matter. The periodic cleaning of a DE filter entails removing and replacing the dirty diatomaceous earth, and often the power washing and/or chemically cleaning of the mesh fabric. It is recommended that this be done by a knowledgeable service technician.