The Importance of Choosing the Right Water Treatment Chemicals for Cooling Towers, Boilers, and Loop Systems

Industrial cooling towers at a chemical plant. These large systems require carefully balanced water treatment to prevent scale, corrosion, and microbial growth.

Industrial facilities rely on cooling towers, boilers, and closed loop systems to keep processes running efficiently. Water in these systems, however, can cause major problems if left untreated. As water circulates and is heated or evaporated, it leaves behind minerals, bacteria, and other contaminants that can lead to scale deposits, corrosion, and biofouling. Even a thin layer of mineral scale, under a millimeter thick, can act as an insulator on heat transfer surfaces, forcing equipment to work harder (e.g. just a 1/32-inch deposit in a cooling system can increase energy use by ~25%). To avoid such inefficiencies and damage, facilities use a range of chemical water treatment products. In this post, we’ll explore the different types of water treatment chemicals – biocides, cleaners, disinfectants, and inhibitors – what they are, their benefits, and how to choose the right ones. We’ll also discuss why partnering with a reliable supplier (like NuChem Corp) can make all the difference in maintaining safe, efficient cooling and boiler operations.

Why Water Treatment Chemicals Are Important

Water is a universal solvent and carrier of contaminants, which means that without treatment, any water-based system will eventually suffer from performance issues or failures. In cooling towers, which are open to the atmosphere, the circulating water picks up airborne dust, debris, and microbes; as water evaporates to reject heat, dissolved minerals concentrate in the remaining water. If not controlled, these minerals precipitate as scale on heat exchanger tubes and tower fill, while dirt and biological organisms form sludge and slime. The result is reduced heat transfer, clogging, and even health hazards like Legionella bacteria growth in the cooling water. Scale buildup not only reduces cooling capacity but also drives up energy consumption dramatically, as mentioned above. Corrosion can soon follow, damaging metal components once protective films are compromised.

In steam and hot water boilers, water is heated to form steam, leaving behind all dissolved solids. As steam generation continues, the concentration of impurities in the remaining water rises, and without proper blowdown and treatment, scale deposits form on boiler surfaces. These deposits act as insulation, causing overheating of metal. Even a relatively thin layer of boiler scale (on the order of 1/8") can increase fuel consumption by around 20%. In extreme cases, overheating leads to boiler tube failure or dangerous pressure excursions. Moreover, corrosive gases like oxygen and carbon dioxide can dissolve in feedwater and attack boiler and condensate lines, causing leaks and shortened equipment life. Without chemical treatment, boilers would face unscheduled downtime, higher operating costs, and safety risks from corrosion and scaling.

Closed loop systems (such as chilled water loops or heating loops) are recirculating systems that may be less exposed to contaminants than cooling towers, but they are not immune to problems. Closed loops can suffer corrosion (if dissolved oxygen or low pH water is present) and even biological fouling if any nutrients or microbes enter the loop. If make-up water or construction debris introduces minerals or dirt, scale and sediment can accumulate in low-flow areas. Even glycol loops require proper conditioning to prevent acidity and corrosion. All these systems “must be treated” – otherwise they inevitably experience corrosion, scale, biofouling, and equipment wear that reduce efficiency and lifespan.

A targeted water treatment program adds specific chemicals to the system water to prevent these issues before they start. Well-designed programs protect cooling and heating equipment from scale, corrosion, and biological fouling by keeping water chemistry in balance. In the next sections, we’ll break down the major categories of chemical products that make this possible.

Types of Water Treatment Chemicals

Effective water treatment involves both preventative treatment chemicals (added continuously or regularly to maintain water quality) and remedial chemicals (used for periodic cleaning or disinfection when problems occur or for maintenance). The key types of chemicals include scale and corrosion inhibitors, biocides, disinfectants, and cleaners. Each type plays a unique role in keeping systems clean and safe.

Scale and Corrosion Inhibitors

Inhibitors are the workhorses of day-to-day water treatment in both cooling and boiler systems, as well as closed loops. These chemicals prevent the formation of scale deposits and protect metal surfaces from corrosion. They are typically fed continuously into the system to maintain a protective water chemistry.

• Scale inhibitors / hardness stabilizers: These chemicals keep dissolved minerals (like calcium, magnesium, silica) in solution or otherwise prevent them from crystallizing into hard scale on surfaces. In cooling towers and open loops, common scale inhibitors include phosphonate compounds and polymers that sequester hardness and disperse precipitates. In boilers, phosphate-based treatments are often used to precipitate calcium in a manageable sludge form, combined with polymers to keep it fluid, thereby avoiding hard scale on boiler tubes. The benefit of scale inhibitors is improved heat transfer efficiency and prevention of costly downtime or fuel wastage due to insulating deposits. (As noted earlier, even thin scale can drastically raise energy usage and cause overheating.)

• Corrosion inhibitors: These chemicals form protective films or alter water chemistry to minimize metal corrosion. Different inhibitors target different metals and system types. For example, nitrite-based inhibitors are commonly used in closed loop HVAC systems to protect steel surfaces by passivating them. In cooling towers, phosphate/phosphonates also help form thin protective layers on steel. For boilers and steam systems, removing oxygen is critical. An oxygen scavenger (like sodium sulfite) is added to chemically consume dissolved oxygen. Boilers also often use alkalinity boosters (e.g. hydroxide or amine-based) to keep pH elevated, which reduces corrosion of iron. In the steam condensate lines, neutralizing amines are fed to neutralize carbonic acid and raise pH, while filming amines may be used to lay down a protective film inside pipes. All these fall under corrosion control chemicals.

  
  

The benefits of using inhibitors are clear. By preventing scale and rust, you maintain efficient heat transfer and extend the life of equipment. For instance, a proper chemical treatment program in a cooling tower “will control scaling and corrosion in the system and provide savings in power cost and improved mechanical efficiency,” whereas untreated systems suffer poor efficiency, high maintenance, and much shorter lifespans. NuChem’s own line of boiler and cooling tower treatment products are formulated to provide “exceptional corrosion and deposit control” for safe and efficient operation. In short, inhibitors are critical for preventative maintenance of water systems.

Biocides for Routine Microbial Control

Biocides are chemicals used to control microbial growth such as bacteria, algae, and fungi found in water systems. Cooling towers, being open recirculating systems, provide ideal warm and wet conditions for microorganisms to thrive, including harmful bacteria like Legionella that causes Legionnaires’ disease. If unchecked, biofilms and algae can foul heat exchangers, clog nozzles, produce slime, and even induce corrosion (microbiologically influenced corrosion). Therefore, continuous or regular biocide treatment is essential in cooling water.

There are two main classes of biocides commonly used in industrial water treatment: oxidizing biocides and non-oxidizing biocides. The difference lies in their mode of action and suitable usage conditions:

• Oxidizing biocides: These kill organisms by oxidizing their cell structures, essentially “burning” through cell walls via chemical reaction. Oxidizing biocides typically release or generate strong oxidants. The most widely used oxidizing agents are chlorine and bromine (often fed as sodium hypochlorite liquid, chlorine gas, bromine tablets, or bromine generated from bromide with an oxidizer). Chlorine is very effective and relatively inexpensive, but it can be corrosive and less stable (chlorine can dissipate in sunlight and is less effective at a higher pH). Bromine is more effective than chlorine at higher pH levels and somewhat less corrosive; it’s often used in towers with alkaline water or where chlorine’s drawbacks want to be avoided. Oxidizing biocides are generally best for routine control of broad-spectrum organisms in water that are continuously recirculated. They tend to act quickly and are good at killing planktonic (free-floating) microbes and disrupting some biofilms.

• Non-oxidizing biocides: These are specialized organic chemicals that kill microorganisms through various biochemical mechanisms (not via oxidation). Non-oxidizers include agents like isothiazolinones, glutaraldehyde, quaternary ammonium compounds (quats), and others. They are often used on a periodic or alternating basis when specific microbial challenges arise or as a supplement to oxidizers. For instance, certain bacteria or fungi might be resistant or sheltered within biofilms such that a non-oxidizing biocide is more effective in penetrating and killing them. Non-oxidizing biocides are also useful when water conditions (like very high organic load, or need to minimize halogen residuals) make chlorine/bromine less effective or undesirable. These biocides might be dosed as a “shock” treatment or intermittently (e.g. one or two times per week) in alternation with an oxidizer to prevent microbes from developing resistance. An example of widely used non-oxidizers is  glutaraldehyde (effective against bacterial slime, including sulfate-reducing bacteria, and often used in cooling tower cleanups). Quaternary ammonium compounds are another class, effective especially on algae and as biodispersants, though they tend to foam and are used carefully.

  
  

Using a combination of biocides or rotating them is the best practice to cover all bases. Continuous low-level dosing of an oxidizer (like maintaining a free chlorine residual) combined with periodic dosing of a non-oxidizer can ensure robust control of microbial growth. The benefits of biocide use include not only protecting equipment (by preventing biofouling that can clog pipes or cause under-deposit corrosion) but also protecting health and safety. Legionella control is a critical aspect of cooling tower maintenance. Many local regulations now mandate regular biocide treatment and testing. In sum, biocides keep the system water hygienic and safe and maintain efficiency by eliminating slimy biofilms that would otherwise insulate surfaces and impede flow.

Disinfectants and Shock Treatments

While biocides maintain day-to-day microbial control, sometimes a system requires a more intensive disinfection procedure. We use the term disinfectants here to refer to chemicals (often the same as biocides but applied in a stronger, targeted way) used for shock disinfection or system sterilization. This is typically done when a system is heavily fouled, has been stagnant, or when a health risk has been identified (for instance, a high Legionella count in a cooling tower test). Disinfection might also be performed as part of routine maintenance (e.g. some facilities do an annual or seasonal disinfection of their cooling system as a preventive measure).

A shock disinfection usually involves dosing a high level of a fast-acting biocide and/or a combination of chemicals to kill all microbial life in the system. For example, a common cooling tower disinfection protocol is to add a biodispersant to loosen biofilm, then chlorinate the system to a high chlorine residual for several hours, circulate, then flush the system. The key is following proper procedures, for instance, protecting personnel (PPE for handling strong oxidants) and ensuring thorough flushing afterwards so the system can return to normal operation safely. After disinfection, heterotrophic (HPC) testing for bacteria counts is often performed to confirm success.

The benefit of a full-system disinfection is that it remediates waterborne pathogens that have grown due to fouling or neglect – it’s essentially hitting the “reset” button on the biological condition of the water. This is the “most potent measure” you can take against a severe bio-growth problem. Many systems never need such drastic measures if they are well-maintained, but when they do (e.g. after extended downtime, or in response to a positive Legionella test), disinfectants ensure the system is safe to operate again.

In boilers and closed loops, full disinfecting is less common (since these systems are not open to constant contamination). However, in a closed loop that has been stagnant or contaminated (say, by a breach or during initial commissioning if microorganisms entered), a one-time disinfectant flush might be done. In a boiler, if someone suspects sulfate-reducing bacteria or other microbes in a low-temperature part of the system (like feedwater tanks or idle boilers), a shock dose of biocide might be applied during a cleaning outage but generally the high operating temperatures sterilize the system in normal use. When we speak of disinfection in water treatment, cooling towers and evaporative condensers are the primary focus due to public health implications.

Cleaning Chemicals (Descalers and Cleaners)

Even with good routine chemical treatment, eventually systems may require physical cleaning to remove accumulated deposits, especially if a system was previously untreated or had a high bacteria count. Cleaning chemicals are used for removing scale, rust, sludge, or biological deposits from the internals of cooling towers, boilers, and loops. These products are typically used off-line (when the system is shut down or taken out of service for maintenance) or in a controlled cleaning procedure, as they often involve strong formulations to dissolve deposits.

The benefit of cleaning chemicals is that they restore system cleanliness and efficiency. After cleaning, surfaces are free of insulating scale and biofilm, so heat exchange is optimal and corrosion under deposits is eliminated. For example, a clean cooling tower or chiller condenser will reject heat as designed, and a cleaned boiler will consume less fuel for the same steam output. Cleaners essentially give your system a “reset” like disinfectants do for microbes but for the physical deposits. It’s worth noting that after a chemical cleaning, it’s important to immediately re-passivate and treat the system with the normal corrosion inhibitors and biocides.

How to Choose the Right Chemical Treatment Program

With so many types of chemicals available, selecting the right treatment program for your specific system is crucial. The optimal choice depends on multiple factors, including the system type (cooling tower vs. high-pressure boiler vs. closed loop), the water source and quality, the metallurgy of the system, operating conditions (temperature, flow, duty cycle), and the particular challenges observed (e.g. heavy biofouling vs. high scaling tendency vs. corrosion issues).

Here are some guidelines on choosing and combining the proper chemicals:

• Identify your water issues: A water analysis and a site survey are the first steps. Determine if your makeup water is hard (high calcium/magnesium) or corrosive (low pH, high dissolved oxygen). Check if there are existing deposits or biological growth in the system. For example, if tests show high bacteria counts or Legionella presence, you know biocide selection is a priority. If you see calcium carbonate scaling potential (high hardness and alkalinity), then strong scale inhibitors will be needed. Each system will have a unique fingerprint of risks that guides the treatment approach.

• Match chemicals to system metallurgy and conditions: The materials of construction (steel, copper, aluminum, etc.) and operating parameters influence chemical choice. Highly corrosive oxidizers like chlorine, for instance, might not be suitable for a system with sensitive components (or they must be tightly controlled). In such cases, alternatives like stabilized bromine or non-oxidizing biocides could be better. If your cooling tower has mostly mild steel, a phosphonate program could be great for corrosion inhibition. For high-pressure boilers, certain treatment chemistries are preferred to avoid carryover and meet steam purity requirements, whereas low-pressure boilers are more forgiving. If a system operates at high temperatures or high cycle concentrations, you will choose chemicals stable under those conditions. Regulatory and environmental constraints also matter, discharge permits might limit use of certain heavy metals or chlorine levels, guiding you to specific product choices.

• Use a comprehensive program: Effective water treatment is multi-faceted. A common mistake is to focus on one problem at a time (say, just toss in a biocide to address slime, or only add a softening agent to address scale), whereas the best strategy is a holistic program that prevents all issues in tandem. For a cooling tower, that typically means using a corrosion/scale inhibitor blends and biocides. For a boiler, it means oxygen scavengers and scale control and condensate treatment. Skimping on one aspect can allow a problem to spiral out of control and undermine the whole system. For example, if you use great scale inhibitors but no biocide in a cooling tower, you might keep heat transfer surfaces free of scale but end up with a biogrowth instead! Or in a closed loop, using corrosion inhibitor without a biocide during initial fill could allow bacteria to proliferate and consume the inhibitor (some bacteria can even feed on nitrite, a common closed loop inhibitor, if a biocide isn’t present). So ensure the program covers corrosion, scaling, and microbial control collectively.

• Consider safety and compatibility: Some chemicals require special handling or may not be compatible with certain system components. For instance, strong oxidizers can degrade certain seal materials if overfed; some dispersants or surfactants could cause foaming if the system has high turbulence; quaternary biocides can be incompatible with polyphosphate scale inhibitors (causing precipitation) if not used carefully. It’s important to choose products that work well together and are safe for your operators to handle.

• Tailor to operating system: An intermittent-use cooling tower (that shuts down in winter) might need a different approach (including a robust winter lay-up procedure) compared to a year-round tower. The more critical and sensitive the system, the more you should invest in high-quality treatment and monitoring.

  
  

Given the complexity of these factors, the wisest course is to consult with water treatment professionals. A knowledgeable water treatment partner will analyze your water and system and recommend the appropriate chemicals in the correct dosages.

Monitoring and adjusting is part of choosing the right chemicals too. Seasonal changes, load variations, or water source changes might require tweaking the chemical regimen. Working with a reliable supplier who offers ongoing service can ensure the program stays optimized through such changes.

Benefits of Partnering with a Reliable Supplier

Considering the importance of proper chemical selection and monitoring, partnering with an experienced water treatment chemical supplier can be a game-changer. A reliable supplier provides more than just chemicals, they bring technical expertise, regulatory knowledge, and support services that help you get the best results from your treatment program.

Here are key benefits of working with a reputable supplier such as NuChem Corp:

• Expert Consultation and System Assessment: A good supplier will start by thoroughly evaluating your systems. NuChem, has trained technical staff that take a “proactive approach in controlling water quality parameters” for customers. They can assist with site inspections and water analysis, helping to pinpoint what chemicals and controls you truly need. This ensures a cost-effective program tailored to your conditions.

• In-house Chemical Formulation and Quality: When a supplier manufactures their chemicals in-house, it can be a big advantage. NuChem Corp manufactures and markets its own line of products. This means they have direct control over quality Additionally, in-house manufacturing often ensures better supply reliability so you can count on having the needed chemicals on time.

• Comprehensive Product Line: NuChem offers a full range of treatment chemicals, from inhibitors to biocides to cleaners, as well as equipment (like feed pumps, controllers, filters) if needed. They also carry industrial cleaning products and specialty chemicals for when you need to do a system cleanout or handle a specific fouling issue. This one-stop-shop capability means you don’t have to juggle multiple vendors; and all the chemicals are designed to be compatible as a program.

• Regulatory Compliance and Safety Knowledge: Industrial water treatment chemicals can be subject to environmental, health, and safety regulations (for example, biocides often must be EPA-registered for Legionella control programs). A seasoned supplier stays on top of these rules. NuChem also keeps up with regulatory matters governing use, handling, and disposal of chemicals. When New York City and State enacted new cooling tower regulations in response to Legionella outbreaks, NuChem had the knowledge and experience to help clients comply. This kind of support is invaluable to avoid fines and ensure safety.

• Ongoing Service and Support: Water treatment is not a one-time transaction; it requires continuous monitoring and adjustment. Partnering with NuChem typically comes with regular service visits by water treatment specialists who test the water on site, review the system’s condition, and adjust chemical dosages or equipment as needed. They can train your facility personnel and provide troubleshooting if an issue arises. They become an extension of your maintenance team. Additionally, they can supply contingency support. If an emergency forces you to shut a system down or you need to do an unplanned cleaning, your water treatment partner can quickly advise on procedures.

  
  

Finally, working with a trusted supplier gives peace of mind. You can focus on your core operations while the water treatment experts manage the complex chemistry in the background. NuChem Corp emphasizes that they are “here to help you with all your chemical needs” and encourages clients to call and speak with their representatives for any concerns. This kind of partnership means you’re never alone in managing your cooling and boiler water you have seasoned professionals on call.

Water is an essential part of cooling and heating systems, but it must be properly treated to avoid turning into a liability. By using the right chemical products you can maximize your system’s efficiency, lifespan, and safety. The key takeaway is that a balanced, well-maintained water chemistry is not an expense but an investment that pays off in lower energy bills, fewer repairs, and reduced downtime.

Implementing an effective water treatment program is much easier when you have the right partner. This is where NuChem Corp can step in to assist. With decades of experience servicing cooling towers, boilers, and loop systems across multiple industries, NuChem has the expertise to diagnose your water challenges and provide you with a chemical treatment program. When you partner with NuChem, you’re gaining a team that will work proactively to protect your assets and keep you in compliance with any regulations.

Ready to get more reliability and performance out of your systems? Contact NuChem Corp today for a free consultation or site inspection. Our water treatment specialists will evaluate your cooling or boiler system and recommend the ideal chemical program to meet your needs. Don’t wait for scale, corrosion, or bacteria to cause costly problems, let us help you take a preventative approach and “ensure safe, clean, and efficient” operations.

Contact Us

Content on the NuChem Corp Blog is for informational purposes only and does not replace professional advice. External sites linked are provided for convenience; NuChem Corp is not responsible for their accuracy or content.