The major advantage of open cooling towers is efficient heat dissipation. However, this comes at a cost: the water is constantly exposed to ambient air. This not only causes evaporation, but also introduces dust, debris, suspended solids, and bacteria. These can lead to fouling, corrosion, and biological problems in the system.
If you want your cooling tower to operate reliably and economically over the long term, water treatment is a must. Here are four key steps that every serious system should include:
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pre-filtration – removing solid contaminants automatically
The first step is to remove physical contaminants such as sand, rust, sludge, and dust. If these remain in the system, they can clog pipes, damage infrastructure, and accelerate biofilm formation.
Recommended solution: automatic pre-filter that
- operates continuously without manual intervention
- self-cleans based on time or pressure difference
- is compact and easy to install
- efficiently removes suspended solids.
This step protects the softener and all downstream components.
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water softening – preventing scale formation
Hard water is one of the biggest enemies of cooling towers. Calcium and magnesium ions deposit on surfaces, reducing heat transfer, increasing energy consumption, and causing long-term damage.
Our Bluesoft industrial continuous water softeners
- provide soft water even during regeneration (no downtime)
- are available in multi-column configurations
- are ideal for high-flow open-loop systems
- ensure stable, hardness-free water
- can be equipped with online hardness monitoring.
This is a reliable and robust long-term solution that significantly reduces maintenance costs.
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ClearGenX – safe disinfection with on-site generated chlorine
Microorganisms from the air (such as algae, bacteria, including legionella) pose serious health and operational risks in open systems. Continuous disinfection is essential.
ClearGenX on-site chlorine generator
- produces active chlorine from salt tablets and water using electrolysis
- eliminates the need for storing or transporting hazardous chemicals
- doses disinfectant automatically
- ensures a stable free chlorine level throughout the system.
Available in multiple capacities (Alpha–Delta models), it can be integrated alongside the pre-filter and softener to form a closed, sustainable treatment solution.
+ optional chemical dosing – when it makes sense
In many cases, physical treatment (filtration, softening, blowdown) and on-site disinfection (ClearGenX) are sufficient. However, depending on system conditions and heat load, chemical treatment may be beneficial.
- antiscalant
Even with softening, some dissolved substances (e.g. silica, phosphate, colloids) can still cause fouling.
In such cases, antiscalant dosing helps by
- keeping salts in solution
- delaying crystallization
- protecting heat exchangers from deposits
- corrosion inhibition
The oxygen-rich environment of open systems can trigger corrosion on metal surfaces, especially with unstable pH or ion concentrations.
Corrosion inhibitors may include
- molybdate, orthophosphate, or silica-based formulations
- protective film formation on metal surfaces
- pH stabilization and corrosion risk reduction
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blowdown – controlling salt concentration and removing contaminants
As water evaporates in the loop, the concentration of dissolved salts increases. Without control, this raises the risk of scaling and corrosion.
Benefits of automatic blowdown
- controlled by a conductivity sensor
- when a threshold is exceeded, the system drains part of the water and refills with fresh water
- helps maintain stable water quality
- reduces chemical consumption and extends equipment life.
Though it’s the final step, it’s essential for sustainable and predictable cooling water operation.
Summary
Pre-filtration, softening, disinfection, and blowdown — these four pillars provide the technological foundation for safe and efficient long-term operation of open cooling towers.
If you’re looking for a water treatment system that truly works not just a theoretical promise, contact us. Hundreds of industrial references, custom solutions across Europe. Fast delivery, reliable technical support, that’s what we’re built on.
