Aqua Master Tools Pen Meter Replacement Electrodes

Replacement pH and EC Electrodes for Aqua Master Pen Meters

These are the replacement electrodes for Aqua Master Tools P50, E50 and P110 pen meters. Each one fits both the current Pro2 model and the original Pro, so check the model name on your meter and pick the matching variant.

The electrode is the part of a meter that wears out. A pH electrode is a thin glass bulb filled with a reference liquid, and that liquid slowly becomes contaminated with use. As it does, readings get slower and less stable, until the meter won't calibrate at all. Replacing the electrode brings the meter back to full accuracy for a fraction of the price of a new one.

EC electrodes last much longer, but limescale, nutrient build-up or a crack in the housing can still stop them reading properly.

These electrodes fit pen meters only. For the H600 Pro, W650 Pro, C800 Pro and P700 Pro2, which use probes on cables, see our Replacement Probes listing.

• P50 pH electrode: for the P50 Pro2 and P50 Pro pH and temperature meters
• E50 EC electrode: for the E50 Pro2 and E50 Pro EC and temperature meters
• P110 pH and EC electrode: one combined electrode for the P110 Pro2 and P110 Pro combo pens
• IP67 waterproof once fitted, the same as the meter
• Six-month warranty on each electrode

Signs your electrode needs replacing

• Readings are slow to settle
• The meter won't accept a calibration, or loses it within days
• Readings jump around in the same sample

Clean the tip and recalibrate first. If the problem stays, it's time for a new electrode.

How to fit it

1. Unscrew the sealing ring at the bottom of the meter.
2. Gently pull the old electrode straight out.
3. Line up the notch on the new electrode so the connectors meet properly, then push it in.
4. Check the rubber seal is seated, and tighten the sealing ring firmly.
5. For pH electrodes, soak the tip in tap water for at least 12 hours.
6. Calibrate the meter before use.

Order online, or use free Click & Collect from your local GroWell shop. If you're not sure which electrode fits your meter, call or message the team with the model name on the back and we'll confirm it.