CTX-500/S AlgaStop Super

If your pool water has turned green or cloudy despite regular chlorination, algae are almost certainly the cause. CTX-500/S AlgaStop Super is a concentrated liquid algaecide formulated by Fluidra to prevent the formation and growth of algae in pool water. With an active ingredient concentration of 7-10%, it is suited to pools where algae pressure is persistent or where a stronger preventive barrier is needed.

What Is CTX-500/S AlgaStop Super?

AlgaStop Super is a fast-acting liquid algaecide manufactured by Fluidra Comercial España under the CTX professional pool-treatment range. The active ingredient is quaternary ammonium compounds (benzyl-C12-16-alkyldimethyl chlorides), present at 7-10% concentration – the defining difference between this «Super» variant and the standard CTX-500, which contains the same compound at 2.5-5%. The product is light blue in colour and supplied in liquid form, available in 5 L and 25 L containers

It targets algae at the formation stage, preventing green, black, and mustard algae from establishing in pool water. It is compatible with all common pool types – above-ground and in-ground – and all standard pool finishes including liner, tile, concrete, and fibreglass.

Ideal for: Pool owners dealing with recurring algae outbreaks or wanting a stronger weekly preventive treatment; suitable for all pool shapes and finishes, above-ground or in-ground.

How CTX-500/S AlgaStop Super Works

The active quaternary ammonium compounds in AlgaStop Super are surface-active agents that disrupt the cell membranes of algae on contact. By attacking the cell wall, the compound prevents algae from forming colonies and spreading across pool surfaces and water. The 7-10% active ingredient concentration means a smaller volume of product delivers the same inhibitory effect compared to lower-concentration formulations.

Because the mechanism is preventive as well as curative, the product works best when applied before algae become visible – at the first sign of reduced water transparency or as a routine weekly maintenance dose. The hazard classification (Skin Corr. 1B; H314 – causes severe skin burns and eye damage; H410 – very toxic to aquatic life with long-lasting effects) reflects the potency of the active compound and underlines the importance of correct dilution and handling before and during application.

How to Apply CTX-500/S AlgaStop Super: Dosing & Treatment Steps

Dose information below is sourced from retailer documentation; consult the manufacturer’s technical data sheet for exact dosing according to your pool type and local conditions.

Initial shock treatment: When the water shows signs of cloudiness or algae are present, dissolve 2 L of AlgaStop Super per 100 m³ of pool water in a container of water first, then spread the diluted mixture evenly across the pool surface.

Weekly maintenance dose: Once the pool is clear, add 0.5 L per 100 m³ of water once every seven days to maintain the preventive barrier.

Application method: Always pre-dilute the product in a container of water before adding it to the pool. Spread the mixture evenly over the water surface. Apply at dusk and ensure no bathers are present during treatment. The 5 L format covers a 100 m³ pool for approximately two initial shock treatments or ten weekly maintenance doses; the 25 L format is suited to larger pools or commercial use.

What to Expect: Timeline & Results

AlgaStop Super is fast-acting. After an initial shock dose, water clarity typically begins to improve within 24-48 hours as algae are disrupted and the filtration system removes dead matter. Run the filter continuously during and after treatment to accelerate clearance.

Frequently Asked Questions