GroStar GS4-E Replacement Electrode

One Combo Probe Restores Every Reading Your GS4 Delivers

A combo pen depends on a combo probe — when the GS4's all-in-one sensor starts to drift, replacing just the electrode brings every one of its five readings back to lab-grade accuracy in a single swap.

The GS4-E pairs a lithium glass membrane with a titanium-alloy build and a double-junction design using blue gel electrolyte — the same combo sensor architecture that gives the GS4 its full measurement range.

Replacing the probe rather than the whole instrument keeps your meter in service longer and your costs down — a routine swap restores accuracy without the expense or waste of buying a new pen.

Key Features & Benefits

• Measures pH, EC, PPM (500), PPM (700), and temperature — matches the readings your GS4 pen is built to deliver, restored to full accuracy.
• Lithium glass and titanium-alloy combo sensor build — is the same sensor technology used in the original instrument, so performance matches what you expect from the pen.
• Double-junction design with blue gel electrolyte — helps the combined pH/EC junction resist clogging, keeping every one of the GS4's five readings stable longer.
• Direct drop-in replacement — installs into your existing GS4 pen with no adapters or tools required.
• 1-year warranty — covers the electrode against defects, giving you confidence in a probe that's built to last.

Who Should Use the GS4-E

This electrode suits GS4 owners whose readings have started drifting or who want a fresh probe on hand — a simple swap restores the pen to like-new accuracy without replacing the whole instrument.

Matching the Electrode to Your Pen

GroStar replacement electrodes are built for 1:1 compatibility with their matching pen — this probe is designed specifically for the GS4. Check your pen's model before ordering to make sure you're getting the electrode built for it.

Frequently Asked Questions

Will this fit my GroStar pen?

This electrode is built as a direct replacement for the GS4 pen specifically — check your pen's model number before ordering to confirm compatibility.

How do I know it's time to replace my probe?

Drifting readings, slow response times, or difficulty calibrating are common signs that a probe has reached the end of its useful life and needs replacing.

Does this single probe restore all five GS4 readings?

Yes — the GS4-E is a combo electrode built to restore pH, EC, PPM (500), PPM (700), and temperature accuracy together, matching the full measurement range of the original GS4 probe.

What's the warranty on the replacement electrode?

It's backed by a 1-year warranty covering defects in materials and workmanship.

Is installation difficult?

No — it's a direct drop-in replacement for the GS4 pen, installing with no adapters or special tools required.