Understanding Cooling System Tests and Critical Parameters

  • 13 August 2019
  • Author: Chem-Aqua, Inc
  • Number of views: 7824

Cooling towers are a critical component in many water systems, providing comfort or process cooling across a broad spectrum of technologies and applications. Cooling towers vary greatly in design and footprint, but all have the main goal: to provide removal of waste heat from processes or building systems. Control parameters are critical to maintaining any cooling system to improve water and energy efficiency, maximize equipment life expectancy, reduce hazards, and minimize downtime.

Many factors such as the system design, operating conditions, makeup water quality, chemical feed and control equipment, on-site monitoring program, and treatment chemicals are considered when specifying the control ranges for a cooling treatment program. Operation outside of these design control parameters can result in problems that:

  • Increase operation, energy, water, and maintenance costs
  • Damage the cooling and/or chiller system
  • Result in system failure

The table below summarizes common cooling treatment tests and their importance to the water treatment program.



Purpose / Corrective Measures*



Hardness and Alkalinity

Water source(s) and water quality can change. Changes impact the control limits for controlling scale and corrosion in cooling systems.

Unexpected makeup changes can result in scale deposits or corrosion in the cooling / condenser system


Used to establish control range for maintaining desired cycles of concentration.

Periodic checks of makeup water confirm the basis for establishing bleed control limits.



Use silica if makeup chlorides are too low for accurate field measurement or to double check cycles based on conductivity.

Tower Water


These parameters are used to monitor bleed requirements. If low, bleed should be reduced. If high, bleed should be increased. Note that increasing bleed will decrease the chemical levels while decreasing the bleed will increase the chemical levels.

Low levels (excessive bleed) wastes water and treatment chemicals, and can cause corrosion. High levels (inadequate bleed) can cause scale deposits and excessive fouling. Scale deposits can result in cooling system failure.



Inhibitor Tests: Molybdenum, Phosphate, Phosphonate

If low, increase feed rate of inhibitor product. If high, decrease feed rate.  If phosphate requirements increase significantly, check for hard water.

Low inhibitor levels can allow scale deposits and corrosion to occur. High inhibitor levels wastes chemicals and can result in phosphonate deposits. Deposits and corrosion can result in cooling system failure.

Microbiological Testing

Regular testing to monitor the effectiveness of the biocide program. High bacterial counts: adjust biocide dosages and/or frequency of biocide additions.

High bacterial counts and/or algae accumulation can lead to fouling, increased energy costs, and excessive corrosion.

Halogen (Free Halogen Residual)

High halogen residual: decrease feedrate of halogen donor product. Low halogen residual: increase feedrate of halogen donor product.

Low halogen level can lead to excessive microbiological growth. High halogen level can lead to degradation of inhibitor and excessive corrosion.


Maintain within recommended limits with proper bleed (if not using acid) or pH control (if using acid).

Low pH can cause corrosion and iron deposits and result in equipment failure. High pH can cause scaling in heat transfer areas.

* Note:  The control measures listed are general and may or may not be the best recommendation for your unique system requirements. Always consult with your water treatment professional to determine proper corrective measures. 

To protect the cooling system and keep heat exchange surfaces clean and free of deposits, process parameters must be monitored and checked regularly.

Effective water treatment is a critical part of the preventative maintenance program for any cooling water system and project ROI. When determining a new water treatment program and critical process parameters, partnering with an experienced solution provider is vital. Chem-Aqua® is a global leader in custom-designed programs for boiler, cooling, and process water systems. Our Total System Approach and comprehensive line of products, equipment, and services that address the unique mechanical, operational, chemical, and people requirements of each system allows us to solve virtually any water-related problem. A customized water treatment program from Chem-Aqua® does more than protect cooling water systems. Focused treatment solutions help maximize the life, efficiency, reliability, and safety of cooling water systems while keeping energy, water, and maintenance costs to a minimum.

To learn more about Chem-Aqua® and our superior line of programs, products, and services, visit www.chemaqua.com today.


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