swim pool society

Cloudy Water

Flocculants, enzymes, and oxidizers

Even though the filter is working properly and the circulation pattern is correct, the pool water can still appear hazy or dull, due to microparticles that are so small that they simply pass through the filter media without being trapped. Add a water clarifier, or enzyme solution to solve this problem. A water clarifier will clump particles together and are easily filtered out. Used regularly, a clarifier will reduce maintenance, improve filter performance and enhance the appearance of the pool water. In severely cloudy water, (spring opening), the use of a flocculant.

Flocculant

A flocculant coagulates the cloudy water particles into masses that settle quickly to the pool floor so that they can be vacuumed up easily.

Flocculants enhance, and are often required to make possible solid-liquid separations from turbid to high percent solids in water. Typically, solid particle sizes in water have a wide normal distribution and are inorganic and organic based. If these particles are denser than water, the particles will settle to the bottom of a container if given sufficient time; however, many of the smaller, lighter particles remain suspended (think a cloudy mud puddle that appears to swirl with activity) for a much longer time than allowed with a typical residence time. That is because the particles, or colloids, are small enough to remain suspended by external forces including Brownian motion (interaction with the water molecules), thermal currents, dispersive surface charges and the like. These are the hardest particles to treat because they are so fine and do not easily and quickly settle.

Unless the particles are uniformly coarse (depending on the water chemistry conditions and relative solid and water densities, coarse particles might be considered greater than 100 mesh or greater than 210 microns) and rapidly settle by gravity, flocculants are required to aggregate multiple particles together as ‘floccules’ which are pseudo-large particles. Enter the flocculants!

Polymers are ubiquitous materials ranging from nylon, polyethylene plastics, Teflon, and starches to amino acids. Flocculants belong to the water soluble polymer class, and so they fully dissolve in water. These are acrylamide based with functionality groups which allow the polymers to readily chemically adsorb to particles. These polymers are very long (for perspective, if you expanded a flocculant molecule to 1 inch in diameter, the total length would be on the order of 1.25 miles long!) As flocculant molecules dissolve in water, these molecular chains (ropes) are free to uncoil and expand, but are never completely linear due to random Brownian motion and water thermal current effects.

In effect, these flocculant ropes lasso aggregates of particles together. Since the polymer chains are very long, these polymers agglomerate multiple colloidal and coarse particles together. As these flocculated aggregates continue to mix, the polymer rope continues pulling the particle aggregate into a tighter and denser floccule, which causes the particles to settle more readily. The larger floccules are more easily filtered, centrifuged and floated in a dissolved air flotation unit.

The initial step of ‘coagulation’ is where a short cationic (positive) charged polymer coagulant is added to partially neutralize the repulsive particle’s negative charges and induces pin flocc aggregation of the colloidal particles. Then the flocculant molecules ‘lasso’ and flocculate these pin floccs into larger floccules.

Enzymes and Oxidizers

Accumulations of body oils, cosmetics and other complex bather waste can result in the buildup of these materials along the waterline and in pipes and filters. This waste can cause unattractive scum lines and interfere with the performance of the sanitizer, a problem that will affect the overall appearance of the water. We recommend the use of enzyme digestive products to control bather waste in the water, and to prevent their buildup on the walls and in equipment. Enzymes help in the breakdown and removal of stains and deeply-set soil.

Enzymes are made up of proteins and amino acids, and they catalyze certain chemical reactions. Our bodies contain countless types of enzymes that help us process food and other things. Pool enzymes are made to break down and digest non-living organics, which makes water cleaner, and chemicals more efficient.

Enzymes are naturally occurring biological catalysts. They help increase the breakdown rate of complex compounds. In pools, specially developed natural based enzymes are used to help break down complex materials like oils and grease. With regular use they will take these very complex and difficult to control materials and break them down into smaller fragments that can be easily destroyed by shock oxidation treatment.

Enzymes work by attracting (or seeking out) a given type of molecule, known as a substrate. The enzyme has a special place that fits that type of substrate and nothing else, and either binds two substrates together, or breaks one apart. Swimming pool enzymes break the non-living organic molecule apart, and digest the carbon bonds, and convert them into CO2. This CO2 then off-gasses as small clusters of bubbles on the pool surface, which is noticeable for several hours after the initial enzyme treatment, called the purge dose.

Chlorine is the primary sanitizer in pools. Killing germs and keeping the pool safe to swim in is the primary purpose of having a residual sanitizer in the first place. Oxidation is chlorine's secondary responsibility, yet the vast majority of contaminants in water are non-living oxidants. That is why enzymes help chlorine work better by eliminating bather waste.

Chlorine and bromine are primary sanitizers and oxidizers for swimming pools. Oxidation is a chemical process where electrons are stolen from an oxidant (like bather waste or metals). In swimming pools, oxidation is basically burning contamination out of the water, but at the expense of chlorine, because along with oxidation comes reduction. Eventually that oxidizer has no more ability to steal electrons, and can therefore no longer oxidize. By the term “chlorine is "used up", we mean it was reduced. Without enzymes, oxidation is virtually the only way for a swimming pool has to rid itself of non-living organics and oils. And while chlorine is an excellent sanitizer, it is a relatively lousy oxidizer.

Downsides of Oxidation

While there are some oxidants that enzymes cannot address–like ammonia and other nitrogen compounds–the vast majority of oxidants in a swimming pool are carbon-based. In other words, non-living organics. These include bather waste like sweat, body oils, saliva and mucous, as well as bather products like lotions, cosmetics, sunscreen and anti-perspirant. The downside is that oxidation reduces chlorine.

Chlorine oxidation is not as effective as enzymes against bather waste. That is why so many pools that rely on chlorine have problems like scum lines and oily water and often struggle with cloudy water. That is why sand filters routinely get fouled with organic grease and grime. These problems often cease to exist when a pool is being treated with multi use products such as CLEAN&CLEAR.

Not all enzymes are well suited to pool use. Many enzyme products are better suited for spas and hot tubs (such as C-Spa). Enzymes are manufactured by living organisms and since chlorine and other sanitizers destroy living substances, it is important to select enzymes that can tolerate the typical sanitizer levels commonly found in pools and spas. Use enzymes that have been properly selected for digestion of the types of oils and greases found in pool water. In spas, the enzyme will help reduce the buildup of organic wastes on filter media and thus reduce the frequency of cleaning as well as improving water appearance.