CALL (414) 425-3339

Request a Site Survey
My water system is scaled up! What should I do to prevent cooling tower or boiler scale?
Favorite this: 
As a water treatment professional, I am used to being blamed for a lot of things. A few months ago, we ran a blog titled STOP! Don’t throw your water treater under the bus. It is an unfortunate reality that chemical treatment is often first to receive blame since the use and application of chemicals is often misunderstood. The truth is usually some type of mechanical failure occurs, resulting in the scale build up. However, this doesn’t mean the water guy is completely out of the woods. In this article we will discuss some of the more common causes and what to do to resolve the problem.
Most towers are treated with either city or well water with makeup hardness levels ranging from 100 to 1,000 ppm of calcium hardness. Others use softened water from softeners or reverse osmosis units that are either blended with some hard water or fed with straight softened water. A last group includes towers that use recycled, reused, wastewater, or some other source that is not common. We will not get into that group today. 

City/Well Supply
– acid is fed to reduce the alkalinity and prevent the calcium carbonate from causing scale on the tower, condenser coils, or heat exchanger. The pH range and alkalinity to run this need to be determined by your water treater using various scaling indexes such as Puckorius, LSI or RSI.  This will vary depending on make-up water quality and system operation. NOT ALL SYSTEMS AND PROGRAMS ARE THE SAME. Here are common problems that can cause scale.
  • pH probe issues
    • This is typically the sole way acid is fed. When the probes are not checked and monitored regularly, they can get out of calibration. When out of calibration you can overfeed or underfeed acid. Underfeed = scale forming conditions. Overfeeding = bigger problems, too much acid for a long enough time will corrode the metallurgy of the tower and coils.
  • pH probe solutions
    • Having redundancy; two probes in line should not fail at the same time. You can visually see when one probe is starting to get out of spec.
    • Online monitoring. Most controllers can be online now. The MAJOR benefit is an alert via email/texts are sent out immediately to your water treatment representative and staff when something needs attention or is out of range.
    • Set a maximum runtime for the acid pump. This will stop the pump and trigger an alarm
    • Regular manual testing of the pH to confirm the probe readings. If you have the manpower!
  • Pump failures
    • Acid pumps take a lot abuse. If the pump fails and you don’t feed acid, scale will build up quickly
    • Inventory is a critical factor as well. Running out of acid can cause days of high pH/Alkalinity quickly leading to scale
  • Improper Water Treatment program
    •  This goes back to what I mentioned earlier about setting up each system properly from the start, with attention paid to the Scaling Indices. NOT ALL SYSTEMS AND PROGRAMS ARE THE SAME.  Just because one set up works in one City, County, or State it does not mean that is the right program for you. This is where you can place the blame directly on your water treater for not matching the program to your specific water quality. In some cases, the water can be so poor that traditional water treatment will not solve the problem. Additional pre-treatment equipment may be required. Trust me, we have been there!
Softened Supply
In general, if scaling is happening on a system that is designed with softened water make-up its related to the softener not working, however, that’s not always the case. To learn some preventive maintenance tips on maintaining your softener, read The Hard Facts: Water Softener Tune-ups Help Maximize Water Quality and Reduce Costs.
Common Soft Water Problems:
  • Process contamination
    • Leaking heat exchanger with hard water getting to the tower.
  • Blend valve issues
    • A lot of systems on soft supply have a blend valve to allow a small amount hardness (10-30 ppm) in the system. If a valve is closed or not functioning that can change the make-up quality.
  • Water Softener
    • No salt in the brine tank.
    • Softener lost power.
    • Softener is in bypass.
    • Softener Control Valves are leaking, not drawing brine, etc. need to be serviced.
All steam boilers need to be on a softened supply of less that 1ppm of hardness for make-up, there is no way around it. Iron scale is also something that can occur. Here are some of the most common causes:
  • Softeners or other pre-treatment not working will cause calcium scale, there is no way around it.
  • Condensate contamination with hard water.
  • Condensate chemical treatment or lack of it will cause iron scale to occur. On the left is a scaled-up boiler tube. On the right are clean tubes free of scale.
On the left is a scaled-up boiler tube. On the right are clean tubes free of scale.
First things first – you need to understand why this happened and fix the root cause of the issue. Continuous descaling of systems is expensive due to energy and gas loss from inefficiency, down time in production, and labor.  Now it’s time to descale your system and get back to normal operation.  
The charts above show how even small amounts of scale reduces system efficiency.
The process is simple but there are risks associated with various methods of treatment. To remove the scale, specialty cleaners or acid is fed and circulated through the system. The type of acid used depends on the kind of scale you are trying to remove.  For example, if there is calcium scale in tower, an inhibited sulfamic acid could be best. If iron needs to be removed from steam boiler tubes, then nitric acid could be used. The type of acid to be used should be determined with help from your water treatment company. On the left is a scaled-up system. On the right is a system that is managed properly showing no scale. Not all systems can be descaled. If the tower scale is so solid that the coils have no gaps or the fill on the side is too solid, not enough water/acid can flow to penetrate the calcium.  To remove scale water must be able to flow through and on all the areas that need cleaning. Before chemically descaling any system it’s best to try and physically chip away and remove as much scale as you can. Warning! Acid is aggressive on scale and metal! If not applied properly, damage to your metal can occur. Ask your water treatment supplier about inhibited acids or specialty cleaners that are not acid based. 
On the left is a scaled-up system. On the right is a system that is managed properly showing no scale.
For a successful descale, the system needs constant recirculation. In some cases, the system recirculation pumps can be used. If not, an external skid system with a storage tank and pump is required. About 1lb of acid will dissolve 1lb of scale.  Since we never know how many pounds of scale are in the system it’s best to go with the 10% rule, for every 100 gallons of water held add 10 gallons of acid. 
Once the acid is added and the water is circulating it’s best to sample the pH of the water regularly. After initial dosing of the acid, the pH should be between 1-3.  As the acid is dissolving the calcium scale, the pH will rise back to neutral pH of 7.  The goal is to keep adding acid until the pH stays below 2 and does not increase. During that process foam will occur. To prevent a giant foam party from happening, a silicone defoamer should be added to the system as needed.  The cleaning process will take several hours. 
The system will need to be drained after, and sometimes during, the cleaning. In many cases you can dump the system to drain. Some municipalities have strict pH discharge limits, so adjustments may be required. Check with your municipality prior to starting the job. 
Nobody wants to descale a system, but we all know accidents happen. It’s key to understand why it happened and find a way to prevent it from happening again. Whether its increased process checks or improved automation and remote monitoring of your water system, do whatever it takes to minimize the cause. This will help your system run as designed, reduce downtime, and improve efficiency. If you have specific concerns about scale in your systems, reach out to us for a Site Survey and one of our technical engineers will be in touch.
Jason Waack, Territory Manager, Watertech of America, Inc.
Jason has over 15 years’ experience in the water treatment industry. He has been a Territory Manager with Watertech for 5 years, managing accounts in the central part of Wisconsin. Jason frequently leads educational training events and seminars to promote better water management and improve safety.

Sign In:
Don't have an account? Sign up:
Forgot your password? Click here
Enter your email address. If an account exists with that address, an email detailing how to reset the password will be sent to it.
Create Account

Already have an account? Log in:
Knowledge Center
Filter Show Filter...
Watertech Knowledge Center
Welcome to the Knowledge Center.
To store favorites or access our entire library, create an account.
Group by Document Type
Favorites Only
Document Type
Case Studies
Company News
Product Information
Technical Documents
Test Procedures
Watertech Employees
Boiler Water
Cooling Water
Potable Water
Food & Beverage
Waste to Energy
Big Cup Golf - Ukraine Benefit
Happy to sponsor and be part of the Big Cup golf event to benefit Ukraine 
Watertech Collects 504lbs for Feeding America
Watertech Supports Feeding America of Eastern Wisconsin 
Save up to 15% on energy costs. EndoTherm can be installed into ANY hydronic heating, process, and chilled loop system. 
Technical document with tips for reopening a building after closure. 
An article from Water Conditioning & Purification that highlights various filtration media, their performance properties and best applications. 
Tufts University School of Medicine found that more than 617,000 hospitalizations from 1991 to 2006 were related to three common opportunistic waterborne pathogens. 
Download the annual surveys from the CDC's National Healthcare Safety Network. 
Watertech is Proud to Support CW4K
Watertech is Proud to Support CW4K 
CMS says WMP's are necessary to be compliant. 
CMS Memo to State Survey Directors 
This toolkit is designed to help people understand which buildings and devices need a Legionella water management program to reduce the risk for Legionnaires’ disease. 
3 Key factors to consider when feeding an emulsion polymer. 
Legionaires' Disease – A problem for health care facilities. 
WTeService Learn More About v3.0
Exciting new updates to WTeService. 
CWT Brochure
When you see CWT you have one of the industry’s best working for you. 
Certified Water Technologists Code of Ethics 
AWT Environmental Statement
AWT Environmental Statement The Association of Water Technologies (AWT) is an association of over 500 U.S. and international water treatment companies that provide water treatment programs for many diverse institutional, commercial and industrial water users. 
An article from Forbes addressing the importance of water to utility industry executives. 
A guide describing a process for assuring that building design intention matches actual energy consumption. 
Map of the U.S. identifying the hardness of water in milligrams per liter in specific locations. 
Guidelines to improve boiler performance allowing you to achieve more cost effective maintenance of a steam system. 
Five examples of how a plate heat exchanger can provide benefits for process heating applications. 
Legionella guide from the World Health Organization. 
Environmental Protection Agency rules governing large and small boilers used at area source facilities. 
Causes and solutions to fouling in heat exchangers.  
Strategies to optimize heat exchanger efficiency. 
Identifying problems that a good water management system can control. 
Boiler logging will reduce accidents, downtime, and equipment loss. 
Scale in boiler water systems is a very common issue. Consult with water treatment specialists to treat and prevent it.  
A list of instrument readings to be taken daily and recorded in your boiler log. 
Energy management basics that should be a part of your everyday checklist routine. 
Partial listing of sizing and installation highlights for steam pressure system safety valves. 
Guide to achieving 50% energy savings toward a net-zero energy building. 
A guide to understanding chemical water treatment in cooling and boiler water systems. 
A brief guide to better understanding boiler water conductivity. 
Information for proper fall shutdown of cooling equipment. 
Decrease your energy costs by using these proven effective guidelines. 
Solutions for water use and energy reduction in order to increase your bottom line and protect the environment. 
Ideas to limit water use in ethanol production utilizing a "reduce, reuse, recycle" frame of mind. 
Understanding our water footprint in order to better conserve water. 
Filtration using step-down particle retention can help reduce operating costs and achieve cleaner solutions. 
Innovative chemistries, optimization of systems and water conservation as these topics relate to scale, corrosion and microbiological prevention. 
Benefits of online benchmarking systems for facilities management. 
Knowing the cost of steam to improve your bottom line. 
Understanding energy metrics to limit energy use. 
New ways to save water in dairy processing. 
Energy reduction strategies for optimizing your bottom line. 
Five helpful tips for integrating environment, health and safety into company culture. 
Different selections of pumps for boiler water applications. 
Reduce your blowdown need to zero and cycle water without limit. 
Identifying key components of the boiler system and how water chemistry relates to Key Performance Indicators.  
Piping dead-legs, source of plant maintenance and safety incidents. 
Necessary steps that need to be taken prior to starting boilers after a lay-up period. 
Ice control and different ice formations in various types of cooling towers. 
Important connections and opportunities between water and energy. 
Guidelines for maintaining optimal water quality in evaporation cooling equipment. 
A checklist for monthly cooling tower maintenance. 
Table of conversion factors. 
10 ways that you can save time and money, prevent litigation and illness, and maybe even save a life as they relate to Legionella.  
Free cooling helps you reduce refrigeration energy consumption by using evaporative cooling equipment to produce chilled water in cool weather. 
Explaining the different types of boiler logs, what these logs can tell you, and who is all responsible for these logs. 
Benefits of using liquid polymers in water-treatment applications and accommodating their unique characteristics. 
Criteria you should consider when evaluating your next cooling tower purchase. 
Tips from Chemical Processing to make fullest use of its hot water, and thus cutting energy consumption. 
Part 1 - Describing some potentially catastrophic events that power and recovery boilers are prone to if not properly maintained. 
Part 2 - Describing some potentially catastrophic events that power and recovery boilers are prone to if not properly maintained. 
Part 3 - Describing some potentially catastrophic events that power and recovery boilers are prone to if not properly maintained. 
General water management guide for facility managers. 
Strategies for reducing energy savings in large office buildings by up to 50%. 
Sustainable and operational benefits of molded, HDPE cooling towers. 
Maintenance requirements to prevent scale from occurring in your boiler. 
Optimization efforts taken by several chemical manufacturers to reduce their water footprint.  
Understanding the key components of cooling towers and how to improve water efficiency. 
How to prevent/minimize Legionella in your water systems. 
Aquassist is a groundbreaking smart water testing tool that will revolutionize how you validate your system’s water quality.  
Seasonal maintenance helps maintain equipment and improve efficiency. 
An account audit helps maintain the success of a water treatment program. 
The importance of becoming a Certified Water Technologist 
Maximize the Potential of Pretreatment 
Aquafilm 1284C treats metal surfaces and not the water to help solve corrosion issues in closed loops.  
Watertech's Polydose line of products improves the efficiency and maintenance of cooling water systems. 
If you want to be the MVP at your facility, huddle up and collaborate with your team.  
RO systems require regular maintenance to maintain their efficiency and effectiveness. 
How to handle large volumes of FOG in your waste stream. 
Learn how Aquafilm effectively treats systems and helps save on energy and water usage.  
Several items should be considered when specifying the proper side stream filtration system. 
5 Things operators ignore, then look to blame on their water treater. 
When working with chemicals, it is important to understand safety procedures and what to do in the event of a chemical release.  
The food and beverage industry is growing, and the demand for water treatment is growing with it.  
This is a great time to review accomplishments and plan for the new year.  
A few adjustments to your boiler or cooling system can save a significant amount of energy.  
Phosphonates can make meeting phosphorus discharge limits even more challenging. 
Learn what to do when you encounter unexpected results with your system's water quality. 
Learn about the negative effects of sub cooled condensate in your heat exchanger.  
Kinetic leaders can help their organization easily pivot and respond to challenges. 
Now is the time to work with your provider to come up with a contingency plan for supply chain challenges. 
Biocides can be used for many applications including healthcare, food & beverage, industrial, and commercial. Choosing the proper disinfection technology is critical. 
Advanced water treatment sensors can improve system performance. 
Cooling tower cleanings are essential for maintaining a safe and healthy cooling system.  
Boiler inspection time is validation time. This is the best opportunity to see how your water treatment program is working.  
Now is the time to ensure your system's HVAC coils are freeze protected and working properly. A frozen coil not only causes water damage, there is also the replacement cost and downtime for repairs when it is least convenient. 
If you want to achieve predictable results from your water treatment program, you need a 3-pronged approach. 
EndoTherm is an additive that is proven to reduce energy usage in heating and cooling closed loop recirculating systems.  
Being proactive and thorough in your approach to maintenance saves time and money in the long run.  
How to manage bacterial growth in cooling towers. 
Aquafilm-V delivers some dramatic results and improvements. 
Many businesses are experiencing delays, shortages and price increases in the wake of the pandemic. 
The regulations are coming. What are you going to do about PFAS / PFOS? 
If you are relying on a municipal water source a dechlorination process may be necessary prior to discharge. 
Is Your Plant’s Pre-Treatment Equipment A Top Priority? For Watertech, it is!  
Guidance and recommended actions for returning water systems to regular use. 
Watertech offers a complete range of flexible business solutions to manage our customers’ needs.  
Watertech offers products and solutions to help meet your sustainability efforts.  
Use these calculations to help determine if it might be time to consider using an Anti-Scalant. 
HVAC cooling tower shutdown and cleaning recommendations from Watertech, OSHA, CDC and CTI.  
Stagnant water in a plumbing system can drastically increase the risk of exposure to Legionella and other harmful water borne pathogens. 
Watertech: Swipe right to build a great vendor relationship! 
What is the Impact of an RO System on a Boiler Water Treatment Program? 
Improving condensate return can save on water, energy and chemicals. 
The Impact of Stagnant Water on Industrial and Potable Water Systems 
Why should water treatment automation be a top priority? 
Happy 40th Anniversary Watertech! 
How to manage your boiler system when results are out of range.  
Give Thanks for Water 
5 Deaerator problems to watch for to help ensure high quality feed water. 
Learn how the salt you choose can have a significant impact on system performance. 
Filming agents prevent scale and corrosion by forming a protective layer on all metal surfaces. 
Tips to keep sensors clean and working effectively to help avoid operational challenges that are costly to correct.  
The number one threat to business development is access to fresh water. This has prompted more to seek careers in the water industry. 
How to manage your cooling system when results are out of range.  
Advancements and innovations in water treatment equipment and controllers make life easier, but more importantly, provide ways to achieve better and more accurate results. 
When boiler water turns to steam solids are left behind. Bottom blowdown and surface blowdown are two methods to reduce solids and help maintain your system. 
Side stream filtration is an important but often overlooked component of an effective cooling water treatment program. 
January is a great time to reassess business strategies and include some water treatment resolutions that could improve the health of your company. 
Water and energy are very much interrelated and dependent upon one another, this co-dependency is called the Water-Energy Nexus. 
Are you considering a chemical-free, cooling water treatment solution? It is important to fully understand your system design and the unique characteristics of your application when making a decision. 
Canned Water for Kids (cW4K) is a great local charity that is making a global impact to help ensure all children have access to clean, safe drinking water. 
Ordering and receiving a glycol delivery should be a fairly straightforward and easy process; however, it takes some insight and planning to avoid complications.  
Making changes in how you use salt in your facility can help protect our fresh water resources, and potentially reduce your operating costs.  
Softeners are a critical component to the water treatment system. They help remove minerals to reduce scale and build-up in piping and heat transfer equipment. 
Sloppy sludge is a challenge in wastewater treatment. It pays to be informed on treatment equipment and how chemicals can impact this process. 
Having a team that has been trained in proper safety procedures and practices ensures not only their own safety, but also the safety of customers. 
The water characteristics of Waukesha’s existing water supply and Lake Michigan water are quite different and will require users to consider how they manage their boiler and cooling water water treatment.. 
Learning how to properly install and maintain your boiler conductivity electrode will help improve the performance of your boiler. 
A holiday blog highlighting 12 days of service in the water industry. Happy 2017. Thank you for your partnership. 
Have You Hugged Your Boiler Today?
How you maintain and operate your steam boiler has a direct effect on the amount of energy, water and chemicals it uses. 
This article outlines a few common problems that can damage or destroy a boiler. Providing proper water treatment and regular maintenance can help prolong equipment life.  
Industrial facilities use large amounts of fresh water. By reducing water usage, facilities also achieve reduced energy cost, chemical cost savings, and other benefits. 
While it is important to be compliant with the latest laws and regulations, the focal point of any effective Water Management Plan should put patient safety first.  
Sanitizers are required in food and beverage facilities. Choosing the right sanitizer can impact wastewater treatment.  
When a vendor relationship is built on trust, good communication, and a sincere investment in your business, it will drive meaningful value and a sustained competitive advantage. 
Choosing the right biocide saves money, by reducing downtime and maintenance costs, and increasing production efficiency.  
The time invested in preparation for cooling system start-up can pay big dividends later in the season. 
Proper preparation in the preseason is critical to ensure system efficiency, sustainability, and dependability. 
An effective employee training strategy can help employees be more productive, confident and boost moral. 
Bioaugmentation can be a game-changer for wastewater management, breaking down organic matter and cleaning up waste streams.  
A comparison of feedwater tanks and deaerators for storing and treating boiler feedwater. 
Waste-to-energy initiatives can greatly benefit communities by mitigating various environmental concerns like pathogen control, odor control, and groundwater contamination.  
A site audit can identify ways to reduce water, chemical, and energy usage.