Commercial Pool and Spa Supplies
Pool Link 500 Series, TAC Probe Gel
Pool Link 500 Series, TAC Probe Gel
SKU:LINK-TACGEL
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The Pool Link 500 Series TAC Probe Gel (Pool Link / Link Automation) is a specialized, catalytic electrolyte gel formulated specifically for the internal reservoir of the Pool Link 500 Series Amperometric Total Available Chlorine (TAC) 0–20 PPM probe.
Unlike standard Free Available Chlorine (FAC) electrolytes that only facilitate direct hypochlorous acid reduction, the TAC electrolyte contains an internal potassium iodide ($\text{KI}$) reagent and buffer matrix. When free chlorine and combined chloramines diffuse through the probe's semi-permeable membrane, they react with the iodide in the gel to form triiodide ($\text{I}_3^-$), which is electrochemically reduced at the working cathode. This provides an ion-conductive pathway to the silver/silver chloride ($\text{Ag/AgCl}$) reference anode and generates a current proportional to total chlorine concentration.
Chemical Formulation & Functional Characteristics
Engineered to maintain stable reaction stoichiometry and baseline conductivity across commercial aquatic operations:
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Catalytic Iodide Buffer Matrix: Formulated with high-purity potassium iodide ($\text{KI}$) in a buffered saline electrolyte base (typically potassium chloride, $KCl$). It maintains a constant internal pH to ensure complete, rapid stoichiometric conversion of combined chloramines into electroactive species.
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Thixotropic Gelled Viscosity: Formulated using high-grade, chemically inert cellulosic or synthetic thickening polymers. The high-viscosity gel resists internal boundary layer drying and prevents electrolyte weep-out through the microporous membrane under line pressure variations up to 50 PSI.
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Light-Sensitive & Anti-Oxidation Chemistry: Compounded to minimize self-oxidation from exposure to ambient light and air. The gel is packaged in amber or opaque containers to prevent premature decomposition of iodide into free iodine.
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De-Aerated Formulation: Treated to eliminate micro-entrained bubbles during bottling, allowing the technician to fill the membrane cap cleanly without air pockets clinging to the cathode face.
Technical Specifications
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Compatible Sensor: Pool Link 500 Series Amperometric Total Available Chlorine (TAC) Probe (0–20 PPM).
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Electrochemical Cell Pairing: Formulated specifically for $\text{Pt-Ag/AgCl}$ or $\text{Au-Ag/AgCl}$ polarographic/amperometric total chlorine cells.
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Operating Temperature Limits: 35°F to 120°F (2°C to 49°C).
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Container Volume: Standard 30 mL to 60 mL (approx. 1 to 2 fl. oz.) opaque squeeze dropper bottles fitted with a fine dispensing tip.
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Service Yield: One 30 mL bottle provides approximately 10 to 15 membrane cap fills (average fill volume is 1.5 mL to 2.5 mL per service).
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Shelf Life & Storage: 12 to 18 months unopened when stored at room temperature (50°F to 77°F / 10°C to 25°C) in a dark, dry location. Depletes faster once opened due to atmospheric oxidation; recap tightly immediately after dispensing.
Close the inlet and outlet isolation valves on the 500 Series acrylic flow cell to relieve line pressure. Loosen the compression gland nut and slide the TAC probe out of the manifold port.
Verification: Flow cell pressure gauge drops to 0 PSI and no water weeps from the open probe port.
Unscrew the old membrane cap counter-clockwise over a waste receptacle and discard the spent electrolyte. Rinse the internal cathode tip with distilled water and gently wipe it with a soft lint-free cloth or lens paper.
Verification: The noble metal cathode surface is bright and free of yellowed iodide staining or mineral deposits.
Fill the new replacement membrane cap approximately 3/4 full with fresh, bubble-free TAC probe electrolyte gel. With the probe held vertically, slide the cap onto the shaft and thread it on slowly to allow excess gel to vent through the relief threads.
Verification: The cap seats flush against the O-ring shoulder, and the membrane face remains flat without trapped air bubbles.
Reinstall the probe in the acrylic manifold, tighten the compression nut, and reopen the bypass valves to restore 0.5 to 1.5 GPM flow. Allow the sensor to polarize electrically under power for 2 to 4 hours before calibrating against a DPD-3/4 photometer test.
Verification: The TAC PPM readout on the Pool Link 501 controller settles into a stable, non-drifting baseline.
Close the inlet and outlet isolation valves on the 500 Series acrylic flow cell to relieve line pressure. Loosen the compression gland nut and slide the TAC probe out of the manifold port.
Verification: Flow cell pressure gauge drops to 0 PSI and no water weeps from the open probe port.
Unscrew the old membrane cap counter-clockwise over a waste receptacle and discard the spent electrolyte. Rinse the internal cathode tip with distilled water and gently wipe it with a soft lint-free cloth or lens paper.
Verification: The noble metal cathode surface is bright and free of yellowed iodide staining or mineral deposits.
Fill the new replacement membrane cap approximately 3/4 full with fresh, bubble-free TAC probe electrolyte gel. With the probe held vertically, slide the cap onto the shaft and thread it on slowly to allow excess gel to vent through the relief threads.
Verification: The cap seats flush against the O-ring shoulder, and the membrane face remains flat without trapped air bubbles.
Reinstall the probe in the acrylic manifold, tighten the compression nut, and reopen the bypass valves to restore 0.5 to 1.5 GPM flow. Allow the sensor to polarize electrically under power for 2 to 4 hours before calibrating against a DPD-3/4 photometer test.
Verification: The TAC PPM readout on the Pool Link 501 controller settles into a stable, non-drifting baseline.
Close the inlet and outlet isolation valves on the 500 Series acrylic flow cell to relieve hydraulic pressure. Unthread the probe's compression collar and extract the sensor body from the manifold.
Verification: Flow cell pressure gauge drops to 0 PSI and no bypass water flows from the open port.
Unscrew the lower membrane cap and discard old electrolyte into a sink or waste container. Rinse the internal cathode tip and cap reservoir thoroughly with distilled or deionized water, then gently blot dry with a lint-free tissue.
Verification: The internal chamber is clean and the cathode surface is free of mineral buildup or discolored gel residue.
Invert the FAC Probe Gel bottle and tap it gently to dislodge air bubbles from the dispensing nozzle. Carefully fill the membrane cap approximately 3/4 full with fresh gel, avoiding micro-bubble entrapment.
Verification: The gel inside the cap is clear, continuous, and free of visible air pockets.
Holding the probe vertically, slowly screw the filled membrane cap onto the probe shaft. Allow excess gel to escape through the pressure-relief threads/vent without forcing or stretching the delicate membrane face.
Verification: The cap is firmly seated against its stop and the outer membrane remains smooth and flat.
Reinstall the probe in the acrylic flow cell, tighten the compression collar, and reopen the bypass valves. Restore steady water flow (0.5 to 1.5 GPM) and let the sensor polarize under power for 1 to 2 hours before running span calibration.
Verification: The FAC reading on the Pool Link 501 controller settles into a stable, non-drifting baseline matching a DPD photometer test.
