Cloudy water/chlorine demand
Water quality is another area of concern. Chlorine demand in saltwater pools (i.e. the condition in which the amount of chlorine generated by the ECG is not enough to overcome the level of organic contaminants in the pool) is often caused by poor salt quality.
Organic contaminants from bather load, yard debris, or other sources will cause pool water to become cloudy if the ECG cannot produce enough chlorine. Since the ECG produces chlorine at a fixed rate, it can be difficult to overcome the chlorine demand caused by a large amount of contaminants. Depending on the magnitude of demand, multiple chlorine shocks may be required to solve the problem.
Inorganic contaminants, as mentioned previously, can also affect water clarity—whether dissolved or suspended in the pool water. This problem can be identified by cloudy water, or, if metal particles are present, the pool water will be discoloured. For example, copper typically causes a green tint, and manganese and iron cause varying brown, blackish and/or purple discolourations.
Removing metal particles is fairly straightforward. It involves using a sequestering agent and filter aid to collect and remove particles. After this is performed, the filter should be cleaned. Removing minerals, e.g. nitrates, calcium, and sulfates, can be accomplished by partially draining the pool and adding fresh water to dilute.
Prevention is the best cure
First, it is important to check with the supplier to learn exactly where and how the salt is manufactured. The supplier should be able to guarantee the quality and consistency of the salt source and production process.
Similar to selecting the appropriate salt, it is important to choose the right maintenance and treatment products as well, as these can either help or create further issues when maintaining a saltwater pool. Therefore, it is important to use products specifically formulated for saltwater pools, without phosphates or sulfates. Phosphates can be found in some anti-scale products and sulfates are found in bisulfate (dry acid), which is often used to lower pH.
Due to the ECG’s high pH, temperature, and chlorine levels, products that are not formulated for saltwater pools can break down in this harsh environment and any phosphates or sulfates present can form additional scale. Further, phosphorous-based compounds also result in the formation of orthophosphates, which are nutrients for algae.
Although phosphate levels in certain treatment products may be minute, it only takes a small amount to cause large-scale problems. For instance, they can combine with calcium to form calcium phosphate, which is a particularly tricky form of scale in that it is not noticeable upon visual inspection, yet can hamper chlorine production significantly.
Some of the more advanced pool salts on the market contain anti-scale and anti-stain agents and are guaranteed to work in saltwater pools. Some even use all three types of scale control mechanisms—dispersion (typically a polymer that adds a positive or negative charge to pool water so mineral ions repel rather than attract); crystal modification (which rounds the edges of mineral molecules so they cannot stack into a cubic scale structure); and chelation (which keeps minerals suspended in water)—for the ultimate protection against scale.
Vendors and distributors can also educate pool professionals about the ingredients in the products they use and why some may be preferred over others. By avoiding harmful contaminates and using the purest pool salt available, pool professionals can guarantee their customers will get the most enjoyment out of their pool.
Bob Harper is vice-president of sales for Compass Minerals’ consumer and industrial business and also serves as general manager of the company’s Pristiva subsidiary. He has 25 years of experience in the pool and spa industry and is an expert in saltwater pool systems. He can be reached via e-mail at harperb@pristiva.net.
