How to Clean Dissolved Oxygen Online Sensor Probes

Dissolved oxygen (DO) online analyzers are critical for water quality monitoring in aquaculture, wastewater treatment, and natural water bodies. Over time, biofilm, silt, grease, or chemical scale can coat the sensor membrane or optical window, causing sluggish response and inaccurate readings. Regular cleaning restores accuracy and extends sensor life.

General Precautions

• Always turn off the analyzer or disconnect power before cleaning.

• Use soft, non‑abrasive materials (e.g., lens cloth, sponge, soft brush).

• Avoid scratching the sensing element (membrane or optical cap).

• Rinse thoroughly with clean water after cleaning.

• Recalibrate the sensor after cleaning.

Cleaning Methods by Sensor Type

1. Electrochemical (Galvanic / Polarographic) Sensors
These have a thin permeable membrane and electrolyte inside.

• Light fouling (mucus, loose algae): Gently rinse with deionized or tap water. Wipe with a soft, damp cloth – never rub hard.

• Grease or oil film: Use a mild detergent solution (e.g., a drop of dish soap in water). Dab gently, then rinse.

• Biological film (biofouling): Soak the probe tip for 5‑10 minutes in a 1% vinegar or 0.1% hydrochloric acid solution, then rinse. Do not use organic solvents (alcohol, acetone) – they damage the membrane.

• Salt or mineral scale: Soak in a 5% citric acid or acetic acid solution for 10‑15 minutes, then rinse.

After cleaning, blot excess water with a soft tissue – do not wipe the membrane.

2. Optical (Luminescent / Fluorescence) Sensors
These use a light‑sensitive patch (spot) covered by a fouling‑resistant layer but still require care.

• Routine cleaning: Wipe the optical window with a soft, lint‑free cloth moistened with clean water.

• Stubborn deposits: Soak the tip in mild detergent solution (2‑5 minutes), then gently wipe.

• Avoid scratching the sensing layer – never use brushes, scouring pads, or strong acids.

• Do not use alcohol or bleach unless specified by the manufacturer; they can degrade the fluorescent dye.

Recommended Cleaning Frequency

• Clean water (drinking water, clean rivers): Every 1‑3 months.

• Surface water with moderate algae: Monthly.

• Wastewater or aquaculture ponds: Every 2‑4 weeks, or weekly during algal blooms.