pH 7 and pH 4 calibration solutions, with distilled water

Regular price 2,300.00 RSD
Regular price Sale price 2,300.00 RSD
766.66 RSD × 3 with no fees

These three bottles are used to calibrate a pH probe at two points: pH 7.0 buffer, pH 4.0 buffer, and the distilled water used to rinse the probe between the two.

Each bottle contains 50 ml of ready-to-use solution, and 3 test tubes are included.

Ref. J6465200·pH measurement and regulation
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The summary

  • What you receive: 3 x 50 ml bottles — pH 7.0 buffer, pH 4.0 buffer and distilled water — and 3 test tubes.
  • What it's for: bringing a pH probe back into line when its readings have drifted from reality.
  • When to do it: every 30 days, at commissioning and after cleaning a probe.
  • Why the distilled water: because a single drop of buffer carried from one bottle to another throws the whole calibration off.
  • Compatible probes: those that calibrate at two points, pH 7 and pH 4.
  • Dispatch: small parcel of liquids, can be grouped with the rest of your order.

Three bottles to recalibrate a pH probe at two points, rinsing included

The response of a pH probe changes over time. Its membrane ages, a deposit forms on it, and the displayed value gradually drifts away from reality. A half-point deviation is invisible on your screen, yet it is enough to trigger gas injection where none was needed. Calibration is the only way to correct this, and these three 50 ml bottles provide everything you need.

🎯 The neutral point first

All pH electrodes are designed to output zero volts at pH 7.0: a new probe reads around 0 mV there, and this voltage drifts from zero as the probe ages. Immersing the probe in this buffer solution allows your meter to measure the offset and correct for it in all subsequent readings. If the probe reads 7.1 in a liquid that is actually 7.0, the meter records that difference once and for all.

📐 The slope, next

The second point, at pH 4.0, serves a different purpose: it tells the device how the probe responds in an acidic environment, that is, the slope of its measurement curve. This is what makes readings reliable in the zone that actually matters to you, between 6.5 and 7, where a planted tank or an aquaponic system is typically managed. A calibration performed at the neutral point alone leaves this zone approximate.

pH 7.0

This bottle provides the neutral point, which corrects the probe's offset.

pH 4.0

This bottle provides the acid point, which sets the slope of the curve.

Distilled water

It is used for rinsing between the two steps, without which the second reading is meaningless.

Always pH 7 before pH 4

Calibration must always follow this order: pH 7.0 buffer first, pH 4.0 buffer second, never the reverse. Starting with pH 4 throws off the probe's zero point, and the JBL controller will reject it with an OFFSET error message; running through the same pH 7 buffer twice will produce a DELTAV error instead. Identify the bottles before opening the menu, and keep them in the same order on the bench throughout.

Replace the electrode when calibration no longer holds true

If calibration fails twice in a row with fresh buffers, the solutions are rarely to blame, as an electrode typically lasts around 24 months. The gel electrode pH probe connects to any BNC socket and comes with its own buffers and test tubes. You can be back to accurate readings the same day, and the kit then serves for monthly recalibrations.

🧪 The process, step by step

Full calibration takes just a few minutes. Pour approximately 10 ml of pH 7.0 into one of the 3 test tubes provided, immerse the probe tip, and confirm on your device once the displayed reading has stabilised. Rinse the tip with distilled water, then repeat the process with pH 4.0 in a second test tube. Discard the remaining liquid from the test tubes rather than pouring it back into the bottles. Replace all three caps straight away, as a buffer solution left open will absorb carbon dioxide from the air and deteriorate as a result. If your device has a temperature probe, immerse it alongside the electrode: it will automatically compensate for the effect of temperature on the reading.

Rinsing with distilled water is essential for the second calibration point to be valid, even if it is often treated as a minor detail. A drop of pH 7 buffer carried over into the pH 4 buffer bottle alters its value, and your meter then calculates an incorrect slope with no warning whatsoever. Tap water is equally unsuitable for rinsing, as it contains its own dissolved minerals and its own pH. Rinse the probe tip with distilled water between the two buffers, and again at the end before returning the electrode to the pond.

🗓️ Recalibration intervals

A probe should be recalibrated every 30 days, and never beyond 60, because it ages continuously and each calibration compensates for that ageing. Recalibrate it after cleaning the tip, after an extended period without use, and as soon as the reading becomes unstable. Each calibration uses 5 to 10 ml of each buffer solution: a 50 ml bottle therefore covers 5 to 10 recalibrations, equivalent to 5 to 10 months at the recommended frequency. A control panel that displays a countdown to the next calibration, such as the CO2 regulation controller, helps you avoid letting the deadline slip.

In aquaponics, a probe reading triggers actions that affect fish, bacteria, and plants simultaneously, such as adding bicarbonate to raise the buffer or making a pH correction. A probe that is off by a few tenths of a unit leads you to adjust water that needed no adjustment at all, and since the working range of an aquaponic system sits around pH 6.8 to 7, those tenths are precisely what matters. Monthly recalibration therefore makes every decision taken in front of the screen reliable, as the article on pH regulation in aquaponics explains.

Technical specifications

What the kit contains

Neutral buffer
pH 7.0, 50 ml
Acid buffer
pH 4.0, 50 ml

Frequency and consumption

Recalibration
Every 30 days60 days at most, always pH 7 first.
By calibration
5 to 10 ml of each buffer solutionThat's 5 to 10 calibrations per kit.

Use

Rinsing
Distilled water, 50 mlTap water has its own pH and skews the second reading.
Sampling
Once out of the bottle, discard after useA drop on the base contaminates the entire bottle.

Reference and compatibility

Manufacturer's reference
JBL 6465200Code EAN 4014162646521
Compatibility
Two-point calibration, pH 7 and 4Some meters require different buffers, 6.86 or 9.18: check your instruction manual.

In the box

  • 1 pH 7.0 buffer solution bottle, 50 ml
  • 1 bottle of pH 4.0 buffer solution, 50 ml
  • 1 bottle of distilled water, 50 ml
  • 3 test tubes

Kit composition, volumes, consumption per calibration and recalibration frequency checked on 07/10/2026 against the JBL manufacturer datasheet, reference 6465200, and the instructions for the controller from the same range.

Estimate your
delivery time

These bottles are dispatched in a small parcel and combine easily with a probe or controller. The exact shipping cost is calculated at the basket stage based on your delivery address.

Frequently asked questions

8 questions

6 key questions, 8 in the detailed view

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