CTX dosing dispensers

CTX dosing units continuously measure the water's chemical parameters using an immersed probe and automatically dispense the corrective chemical. When the electrode detects a deviation from the programmed set point, the circuit activates the peristaltic motor to pump pH reducer or increaser from the container into the return pipe.

This mechanism uses proportional dosing, injecting shorter pulses as the water approaches the optimal level. Injection always takes place after the filtration and heating system to protect technical components from direct exposure to acidic concentrations.

For a 50-cubic-meter pool with salt electrolysis, the CTX pH-regulating peristaltic pump, with a flow rate of 1.5 l/h to 1.6 l/h, offers precise technical sizing. Salt electrolysis naturally tends to raise pH, so it requires constant, gradual acid correction.

CTX E-Series or Mypool Dos units take readings using a glass electrode and deliver the exact volume of liquid pH reducer. If you're looking for a technical panel-mount alternative for your control panel, you can consider the POOL BASIC panel-mount peristaltic pump, 1.5 l/h flow rate, which offers the same volumetric flow standard for standard residential installations.

The main difference lies in the type of chemical administered and the flow control method.

• CTX peristaltic dosing unit: It uses a rotor with rollers that compress a flexible Santoprene tube to draw liquid pH reducer or chlorine from an external container. It is activated only by the electronic probe reading.
• In-line chlorine feeder: This is a sealed, rigid tank installed in the pipe, into which solid tablets are placed. They dissolve as water continuously flows through, as with the Hayward 2.5 kg in-line chlorine feeder.

The peristaltic system offers millimetric precision compared with the passive dissolution system, preventing sudden imbalances in the pool water.

Electrode calibration on CTX dosing units requires prior adjustment using clean reference solutions before immersing the probe in the pipe.

• Stop the filtration pump and close the probe-holder valves to isolate the hydraulic circuit.
• Remove the pH sensor and rinse the glass bulb with distilled water, drying it with a soft paper towel without rubbing.
• Immerse the electrode in the pH 7 buffer solution, open the unit’s calibration menu, and confirm once the reading stabilizes.
• Repeat the sequence using the pH 4 buffer to complete the slope adjustment and ensure accurate readings throughout the season.

Following this procedure at the start of 2026 prevents injection errors that could lead to unnecessary chemical use.

The compression tube inside the pump, made of Santoprene, should be replaced once a year to prevent mechanical fatigue failures or loss of suction. The continuous action of the rotating rollers degrades the elastomer’s elasticity, progressively reducing the nominal pumping capacity of 1.5 l/h.

During the annual inspection, it is essential to lubricate the roller assembly with silicone grease and check that the injection valve is not clogged with limescale. Regular preventive maintenance eliminates the risk of corrosive liquid leaking inside the dosing pump housing.

Installing a CTX dosing unit is straightforward for anyone with basic pool plumbing and electrical skills. The kit includes pipe saddles for 50 mm pipe, injection fittings, a foot filter with a check valve, and a wall-mounting bracket.

Electrically, the unit must be connected in parallel with the recirculation pump contactor in the control panel. This synchronization is essential to ensure the dosing unit never injects reducing chemicals while the water is stagnant in the pipes. In the hydraulic layout, the probe should always be positioned before the filter or in the analysis bypass, while the acid injection valve is installed at the end of the return circuit to the inlets.

The standard setpoint on a CTX dosing unit should be fixed between 7.2 and 7.4. Maintaining this precise range ensures the disinfectant retains more than 70% of its active biocidal efficacy against bacteria and algae growth.

If the level drops below 7.0, the water becomes corrosive and can damage heat exchangers, seals, and lights. Conversely, readings above 7.6 cause limescale deposits and cloudy water, and drastically reduce the disinfection capacity of the available chlorine.