CTX-500 AlgaStop

If your pool water has turned green or cloudy despite your usual treatment routine, the problem is almost always the proliferation of chlorine-resistant algae. CTX-500 AlgaStop is a fast-acting liquid algaecide, formulated with quaternary ammonium compounds, suitable for both in-ground and above-ground pools. With triple bactericidal, algaecidal and fungicidal action, it works preventively and as an initial shock treatment whenever water clarity deteriorates.

When your pool turns green: causes and signs of algae

Algae develop rapidly when intense sunlight, high temperatures and insufficient chlorine levels combine. The visible result is water with a green tint, cloudiness or deposits on the walls – clear signs that the chemical balance has been disrupted. Both in-ground and above-ground pools are equally susceptible, particularly during the summer months or after heavy rainfall that dilutes disinfection products.

Long-term users of CTX-500 AlgaStop report consistent effectiveness in algae control, with no structural issues associated with the product. Weekly preventive treatment is the most effective way to stop the situation from ever reaching the point where a full shock dose is required.

How CTX-500 AlgaStop works: fast and multi-action formula

AlgaStop is a light blue liquid formulated with quaternary ammonium compounds – the class of active ingredients that combines bactericidal, algaecidal and fungicidal power in a single application. Quaternary ammonium acts on the cell membranes of microorganisms, destroying them rapidly and preventing re-establishment.

This triple action means the product does not simply eliminate visible algae: it also acts on bacteria and fungi present in the water, contributing to a more thorough sanitisation. The liquid formulation allows for even distribution across the pool surface and rapid dissolution throughout the body of water.

Dosage and application instructions for CTX-500 AlgaStop

Manufacturer CTX specifies two dosage regimes, both published in the official technical data sheet:

Initial treatment (shock): add 2 litres of AlgaStop per 100 m³ of water. This treatment should be repeated whenever the water lacks transparency.

Maintenance treatment: add 0.5 litres per 100 m³ of water, once per week.

Application method: pour the required dose into a container with water and spread the solution evenly across the pool surface. Application should preferably be carried out at dusk and without bathers in the water. This procedure maximises product effectiveness and minimises direct exposure.

The doses indicated are guidelines and may be adjusted according to the specific characteristics of each pool, local climate and degree of contamination.

Available sizes and formats

• 5-litre container – suitable for residential pools with seasonal maintenance;
• 25-litre container – economical format for larger-volume pools or professional use;

Frequently asked questions