by jason_cramp | March 3, 2021 2:09 pm
Proper pool care is based on three important Ps: prevent disease, protect equipment, and provide the expected swimming experience. Maintaining adequate sanitation is a key element to proper pool and spa maintenance as it keeps bathers safe from disease and allows for clean, clear water. Using an oxidizer on a weekly basis, adding a preventative algaecide, good physical maintenance, and select ancillary products round out the key components of a program that maximizes the impact of the sanitizer and helps provide the expected environment for swimmers.
There are many different sanitizer options for pools that include chlorine, bromine, salt chlorination, and biguanide. While each offers a different range of features and benefits, chlorine sanitization is the most common choice for pools and spas due to its ease of use and impact on water balance. Chlorine can be introduced to the water in many ways, including sticks, tablets, granules, liquid, and chlorine generator systems. Regardless of which version is being used, each method leads to the formation of hypochlorous acid. Hypochlorous acid is the killing form of chlorine that does the work of preventing disease and maintaining the expected safe and clear environment in the pool or spa water.
Since all forms of chlorine lead to the same sanitizing compound, the features and benefits among the different options are focused on the secondary impact of the chlorine type on overall water chemistry.
Service professionals and homeowners make sanitizer choices based on many different factors. For example, trichlor comes in slow dissolving sticks or tablets, making it the perfect choice for feeding through a chlorinator, while also reducing the number of trips one must go poolside for application. It is important to understand trichlor also has a low pH and can impact total alkalinity and pH readings.
Dichlor, on the other hand, is a quick-dissolving granule product that can be broadcast directly to the pool. Dichlor does not impact water balance, but it must be applied several times a week if it is being used as the primary sanitizer.
Trichlor and dichlor are both stabilized chlorine products. The primary difference between a stabilized and unstabilized chlorine product is the presence of cyanuric acid. Chlorine is not ultraviolet (UV) stable. This means on its own, chlorine will degrade in the presence of sunlight rather quickly. Stabilizer protects chlorine from UV rays, and stabilized chlorine will last five to six times longer than unstabilized chlorine. As a result, bathers will be protected longer when stabilizer is present, or when stabilized chlorine products are used consistently to sanitize recreational water.
Sodium hypochlorite, or liquid chlorine, is inexpensive and easy to apply to the pool, but it has an extremely high pH that results in the need for routine application of a pH decreaser to maintain proper water balance. Calcium hypochlorite is available in tablet and granule form, giving a wide variety of application options. It is important to know the pH of calcium hypochlorite is high, and the granules often require pre-dissolving before adding the product to the water.
Hypochlorite products do not contain stabilizer, so stabilizer must be added directly to the pool to provide protection from UV degradation when using these products.
Due to current industry conditions, the use of liquid chlorine will become more prevalent for the upcoming pool season. This may be a new approach to sanitizing for many pool care professionals, so it is a good idea to review the features of liquid chlorine and how to maximize it as a sanitizer in a pool.
Liquid chlorine, also known as sodium hypochlorite, is an unstabilized sanitizer with a pH of around 13. The benefits of liquid chlorine include its cost effectiveness, as well as the ease of application as it can be simply poured into the pool without concern that it will bleach the surface.
As it is unstabilized, when using liquid chlorine as the primary sanitizer it is important for service technicians to check and balance the cyanuric acid independently of the sanitizer application. A residual of 30 to 50 parts per million (ppm) of stabilizer is ideal to maximize the life of liquid chlorine and to protect it from UV degradation once it is added to the pool.
Even with adequate stabilizer levels, liquid chlorine must be added frequently to maintain the required 1 to 4 ppm sanitizer residual needed to provide adequate sanitization for the pool.
In addition to stabilizer, there are other components and ancillary products to consider for maximizing the effectiveness of liquid chlorine. For instance, water balance can play a big part. As the pH of liquid chlorine is around 13, this will drive the water’s pH upward with each application. When the pH of the water is high, chlorine is not as active as it should be, which makes it less effective. The industry recognized correction factor is 295.7 to 473 mL (10 to 16 fl oz) of muriatic acid for every 3.78 L (1 gal) of liquid chlorine added to maintain the water’s pH in the range of 7.2 to 7.6, which is necessary to ensure chlorine is active and effective in the pool.
In addition to balancing the water, there are other products that can be added to a routine pool care program to maximize the impact of liquid chlorine. A preventative algaecide, which should be a part of any pool care maintenance program, is an important addition when trying to maintain an adequate chlorine residual—especially when using liquid chlorine.
Adding an algaecide weekly allows chlorine to be used for killing bacteria rather than ridding the pool of algae. The less work chlorine needs to do in the pool, the longer it will last. Therefore, it is important service professionals choose the right preventative algaecide—especially if water features or attached spas are present as some algaecides could cause excessive foaming. In these cases, it is important service technicians refer to the label instructions for guidance.
The addition of an enzyme product on a weekly basis will also enhance the efficiency of any chlorine-based pool maintenance program. Enzymes break down non-living waste that is typically oxidized by higher levels of chlorine or a non-chlorine oxidizer. By using enzymes to break down non-living waste (e.g. sunscreens, hair products, body oils, pollen, etc.) present in pool or spa water, the demand on chlorine is reduced. Less chlorine needed to maintain a residual is often evident in a maintenance program that uses enzymes consistently for this purpose.
Another option for service professionals to improve water quality and ensure success with liquid chlorine is orthophosphate removal. When the phosphate level gets too high (roughly over 125 ppb), it can create dull, cloudy, or hazy water conditions and, in combination with high pH and calcium hardness, contributes to the formation of calcium phosphate scale on surfaces and equipment.
This is especially problematic for saltwater pools. Since phosphate is the last step in the oxidation process of phosphorous, chlorine and shocks do not influence it; however, phosphate does contribute to the conditions that make it harder for chlorine and algaecide to do their jobs. Therefore, keeping a pool at a near-zero phosphate residual is the ideal goal.
Testing for and removing phosphate proactively helps reduce reoccurring pool problems, simplifies maintenance needs, and improves the look and feel of the water. Service technicians should use multi-functional weekly maintenance products that will add enzymes and phosphate removers at the same time. This will maximize the potential of liquid chlorine and, at the same time, minimize the time needed poolside to perform water maintenance as well as reduce the number of different products that need to be added the water.
Often, the first tool a service professional reaches for when poolside is a chemical. However, the value of improving or expanding routine physical maintenance to maximize a pool care program is by far one of the most overlooked solutions by service professionals and pool owners alike.
The benefits of properly circulating pool water, providing good filtration, and even getting in a light personal workout by brushing and vacuuming, is often understated.
If the sanitizer, or any other ancillary chemicals applied to the water, cannot reach problematic areas then the opportunity for water quality issues increases and the value of those water care products are reduced. Specifically, for a sanitizer, if it cannot reach it, it cannot kill it.
Traditionally, pool water needed to be circulated 10 to 12 hours a day and turnover the volume of the pool at least twice in a 24-hour period. However, with variable speed pumps (VSPs) allowing consumers to run their pumps for longer periods without breaking the bank, the standard 10 to 12 hours is more complex and flow patterns become more important.
Most consider the positioning of pool returns as an afterthought and think the more churn and surface disruption, the better. In many cases this is not true. For instance, larger above-ground pools can struggle to maintain good circulation since the lack of a main drain and limited amount of surface skimmers makes it more difficult. Many also have returns improperly positioned to point up toward the surface of the pool to make water appear to be circulating vigorously.
Despite looking great, the circulation is inadequate and leads to problems occurring faster at the bottom and centre of the pool. These areas of reduced circulation become the landing spot for large amounts of debris, while areas such as the seams (where the pool floor meets the walls) become a haven for the start of biofilm and algae growth. What collects in these dead spots consumes chlorine-based sanitizers that blindly attempt to react and break down nitrogen-rich pool contaminants.
With good circulation in place, a pool ecosystem relies on proper filtration to remove debris and other contaminants from the water. The physical and biological processes occurring inside the filter increase the demand on the sanitizer and make it less efficient by performing activities outside of sanitization.
As the filter performs its primary job, the contaminants fill the empty space between media—whether they are pores in a cartridge or the space between granules of sand, glass, and diatomaceous earth (DE). This increases the media’s ability to filter smaller and smaller particles which improves clarity; however, flow inside begins to decrease as pressure within the system increases. Over time, the efficiency of the media is reduced, increasing the opportunity for biofilm growth within the filter. Certain micro-organisms can produce byproducts that increase the demand on a chlorine-based sanitizer.
Routine filter maintenance such as backwashing or rinsing cartridges will remove loose accumulations. Periodic chemical filter cleaning during the season removes the more difficult greases, oils, and scale that reduce filter effectiveness. Service technicians should be mindful not all filter cleaners work for every type of accumulation. Therefore, it is important to read labels and directions carefully before treatment.
Another method to increase chemical efficiency by keeping a clean filter is to incorporate products into weekly service that help reduce the filter load. Routine use of enzyme-based products can be an effective tool to help break down non-living organic accumulations in the filter media and provide longer filter cycles between cleanings. Most enzyme-based products also contain surfactants that not only help keep a filter clean, but also aid in other problematic areas of the pool as well.
One of the more unsightly and most recognized sources of frustration that can lead to increased sanitizer usage is the formation of waterlines on the pool surface. Oils, greases, and other wastes enter the pool water from bathers and most float on the surface.
These nuisance contaminants mix with other debris that float and begin to accumulate on the pool walls, creating an unpleasant waterline that can also collect bacteria and algae. Brushing is the most effective way to break down these accumulations and get them back into the bulk solution of the pool before they cause a problem.
Other areas of the pool also provide favourable conditions for accumulations that can lead to larger issues. Dead spots are areas of the pool where circulation is poor due to a variety of reasons, such as the pool’s shape and structure, special features, and other in-pool accessories. For vinyl pools, certain seam locations can also provide a favourable surface for accumulations to develop.
These areas should be brushed at least once a week to keep surfaces clean. The use of water tension modifiers can also help keep these areas clean. Certain algaecides and most enzyme-based products contain surfactants that modify water tension, helping to pull debris off surfaces and back into the water where it can be removed by the filter or broken down further by treatment products.
Common areas to watch for buildup of debris, algae, or biofilm growth include:
With the use of liquid chlorine likely being more common for the upcoming pool season due to limited availability of other sanitizers and oxidizers, certain modifications to routines and practices should be made to maximize the effectiveness of the product being used. This should be done safely with proper storage and handling of products.
One of the larger differences between sodium hypochlorite and other solid chlorinating compounds, such as calcium hypochlorite, trichlor, and dichlor, is how storage conditions can impact product degradation. Bleach concentration and storage temperature play a large role in the loss of product strength. Generally, increased temperatures will accelerate the process for all strengths, and higher concentrations will degrade at a faster rate. It is recommended to store liquid bleach in tightly closed containers out of direct sunlight in a dark cool place. Further, in warehouses, liquid bleach should never be stored over solids. It is a good practice to store inert materials, such as hoses or handhelds, in-between liquid bleach storage and other chemicals.
When adding liquid chlorine to the pool, service technicians should pour slowly to avoid splashing. It is strongly recommended for one to wear gloves and goggles when handling and applying the product. Liquid chlorine is corrosive, so it may cause skin and eye irritation as well as damage clothing. Finally, before a service technician discards any used containers, it is a good practice for one to rinse the containers out before discarding them in the trash.
Transporting large quantities of liquid chlorine on service trucks also requires a modification to the normal routine. It should never be transported in the passenger compartment and, to protect against incompatibilities, use of an approved secondary container is recommended as a safeguard in the case of spills or leaks.
It is also important to note sodium hypochlorite should never come into direct contact with acids or ammonia-containing compounds. Mixing them could result in the formation of harmful gases, which could lead to breathing difficulties.
Transport Canada/U.S. Department of Transportation (DOT) regulations may be different for each province/state, sometimes even for individual municipalities/counties. Therefore, it is the responsibility of the vehicle driver to know and comply with all transportation regulations. This also means following the proper requirements for signage on service vehicles. Service technicians must be sure to follow all pertinent regulations for the placarding of hazardous materials for transport. Service technicians should refer to Transport Canada/U.S. Department of Transportation (DOT) regulations as it pertains to proper placarding procedures and exemptions.
General guidelines include:
From a chemical standpoint, liquid chlorine can be an effective element of the weekly pool care maintenance program and is a capable weekly sanitizer. However, since it must be added frequently to maintain the proper chlorine residual, anything that can be done to extend the life or enhance the effectiveness of liquid chlorine is a valuable addition to the program.
Balanced water, preventative algaecides, enzymes, and phosphate removers all contribute to creating the ideal environment for liquid chlorine to be successful. In addition, proper physical maintenance, as well as storage and handling, are necessary to maximize the pool maintenance program and minimize the work necessary to protect swimmers and provide the expected environment. An all-inclusive pool maintenance program is the key to success.
[6]Alicia Stephens is the education and training manager for Biolab Inc. In her 20 years with the company, she has focused primarily on education, training, and development, as well as technical support and new product research and integration. Currently, Stephens supports all education and training initiatives for the Biolab Pro Dealer division. She can be reached via email at alicia.stephens@biolabinc.com[7].
[8]Brian Trenck is the technical services team lead for Biolab’s research and development (R&D) group. With more than 23 years with the company, he provides product application expertise and product troubleshooting for new product development. Trenck is dedicated to technical training and problem-solving for internal and external customers. He also serves as the subject matter expert for water testing software and hardware. Trenck can be reached via email at brian.trenck@biolabinc.com[9].
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