Antiscalants & hardness stabilizers - protection against deposits, precipitation & system failures

Antiscalants (also known as scaling inhibitors) are special additives that prevent the formation of poorly soluble salts - so-called scalings - in water-bearing systems. These include, for example, calcium carbonate (lime), calcium sulphate (gypsum), barium and strontium sulphate, iron hydroxide or silicates.

Antiscalants work through the threshold effect: even at very low concentrations (ppm range), they prevent the crystallization of dissolved ions. They block nucleation, disrupt crystal growth and keep the salts in solution or disperse incipient precipitation.

These mechanisms of action enable increased tolerance to hardness formers without the need for complex softening or decarbonization - economical, energy-saving and reliable.

The threshold effect describes the ability of certain substances to suppress the crystallization of dissolved ions even at extremely low doses - well below the stoichiometrically required amount.

Example: With just 5-10 ppm of a suitable antiscalant, the precipitation of several hundred ppm of calcium carbonate or calcium sulphate can be prevented. This effect can only be achieved with specially formulated additives with high surface activity and complexing ability.

The threshold effect is particularly important in membrane systems, cooling circuits, hot water systems or wherever high ion concentrations meet small surfaces, high temperatures or pH fluctuations.

Our products are used in almost all industrial water systems - especially where:

• concentration processes (evaporation, reverse osmosis) take place

• High temperatures can lead to precipitation

• High raw water hardness cannot be removed economically

• Deposits jeopardize operational safety and efficiency

Typical areas of application are

• Reverse osmosis (RO) systems - Prevention of membrane blockage

• Cooling circuits - prevention of lime precipitation and gypsum formation

• Boiler and steam systems - reduction of scale and overheating

• Circuits with strongly varying water quality (e.g. river water or mixed water)

• Process water in the food, chemical, plastics or metal industries

Our products cover a wide range of typical inorganic deposits:

• Calcium carbonate (lime) - very common in cooling and hot water circuits

• Calcium sulphate (gypsum) - in evaporation-intensive systems (power plants, dryers)

• Barium sulphate / strontium sulphate - in well, process or recycling water

• Iron & manganese compounds - oxidized iron forms during aeration or pH increase

• Silicon dioxide / silicates - particularly critical for RO systems and increased conductivity

• Magnesium compounds - especially with high pH values in circuits

Special combinations of phosphonates, polymer systems, dispersants and complexing agents reliably stabilize even poorly soluble or aggressive scalings.

The dosage depends on the ion composition of the water, the concentration factor (e.g. in RO systems) and the operating mode of the system.

Typical dosing ranges:

• Reverse osmosis: 2-8 ppm (depending on Ca, Mg, Si, Ba, Sr, Fe)

• Cooling water: 10-30 ppm (depending on KH, pH, temperature)

• Steam/boiler systems: needs-based conditioning depending on the feed water

We supply suitable dosing calculations based on your water analysis and provide dosing stations with monitoring and alarm functions on request. In membrane systems, the product is ideally added upstream (e.g. with mixed water or permeate) before the high-pressure pump.

Yes - our antiscalants are fully compatible with:

• Corrosion inhibitors (e.g. phosphonates, molybdates)

• Biocides (oxidative and non-oxidative, depending on the formulation)

• Dispersants & cleaning additives

• pH regulating agents and alkalizing agents

• O₂ binders in boiler applications

Our combination products sometimes combine several mechanisms of action in one solution (e.g. antiscalant + corrosion protection + biofilm control). In RO systems in particular, we test the chemical compatibility with membrane materials (e.g. polyamide, cellulose acetate) in advance.

Phosphonates are classic Threshold active ingredients with an excellent effect against lime and gypsum. They also act as corrosion inhibitors and are very efficient when dosed correctly.

Polymers such as polyacrylates or maleic acid copolymers increase dirt dispersion, improve layer formation and prevent the agglomeration of crystals that have already formed. They are more temperature and pH stable than many classic formulations.

The optimum combination of both systems enables:

• Higher tolerance to limit water qualities

• Less cleaning & maintenance

• Better performance even under changing operating conditions

Yes - we offer environmentally friendly antiscalants that:

• phosphate-free / low phosphonate

• Biodegradable according to OECD 301/302

• Free from heavy metals & AOX-relevant substances

• Non-toxic for aquatic organisms

These products are ideal for direct dischargers, food processing plants, condensing boilers or applications with special disposal requirements. We also provide suitable formulations for OEM partners or export markets with specific environmental requirements.

Typical indications of deposition problems:

• Pressure increase in the system (e.g. upstream of membranes or heat exchangers)

• Decreasing heat transfer / increasing outlet temperature

• Visible deposits on fittings or pipes

• Irregular flows / blockages

• Shortened cleaning cycles or frequent system malfunctions

We offer as a service:

• Coating analysis in the laboratory

• Online monitoring of scaling indicators (e.g. conductivity, differential pressure)

• Dosing optimization based on SI index, LSI, STAS or proprietary prediction models

The use of antiscalants and hardness stabilizers is subject to various technical regulations and legal requirements. These are particularly relevant:

• VDI 2035 (sheets 1 & 2): Regulates water quality in heating systems, including limit values for hardness and conductivity.

• PED (Pressure Equipment Directive): Specifications on material compatibility and system operation, relevant in boiler and steam systems.

• TA Luft & Water Resources Act (WHG): Especially for direct discharge, waste water treatment or products containing phosphate.

• Membrane manufacturer specifications (e.g. for RO systems): Permissible application concentrations, pH ranges and compatibility with membrane materials (polyamide, CTA etc.).

• Food and pharmaceutical industry: Use only safe, FDA/BfR-listed or HACCP-compatible additives.

Our products meet these requirements and we can provide all relevant evidence (safety data sheets, standard references, manufacturer approvals) on request. In addition, we advise on the compliant design of water parameters and document the additive application - also digitally, if required.