JBL ProFlora CO2 Calibration Set box, pH probe calibration kit with its illustrated bottles

The three JBL ProFlora bottles lined up: pH 4 buffer solution, pH 7 buffer solution and distilled water

JBL ProFlora calibration kit unpacked, pH 7, pH 4 and distilled water bottles in front of the box and cups

JBL ProFlora pH calibration kit, pH 7 and pH 4 buffers

Name: JBL ProFlora pH calibration kit, pH 7 and pH 4 buffers
Brand: JBL
SKU: J6465200
Price: 18.9 EUR
Availability: InStock

18,90 €

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·Aquarium CO2

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The summary

What you receive: 3 bottles of 50 ml, pH 7.0 buffer, pH 4.0 buffer and distilled water, and 3 test cups.
What it is for: recalibrating a pH probe whose reading has drifted from the true value.
When to do it: every 30 days, at commissioning and after cleaning the probe.
Why distilled water: a drop of buffer carried from one bottle to the other skews the second point.
Which probes: those that are calibrated at two points, at pH 7 and pH 4.
Shipping: small parcel of liquids, tracked, costs calculated at checkout.

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

The JBL ProFlora pH calibration kit is used to recalibrate a pH probe whose reading has drifted from the true value. It includes 3 bottles of 50 ml (pH 7.0 buffer, pH 4.0 buffer and distilled water) and 3 test tubes. The pH 7 solution corrects the offset, while the pH 4 solution sets the slope. Repeat every 30 days.

A pH probe's response changes over time. Its membrane ages, a deposit forms on it, and the displayed value gradually drifts from reality. A deviation of half a point is not visible on your screen, yet it is enough to trigger an unnecessary CO2 injection. Calibration is the only way to correct it, and these three 50 ml bottles provide everything you need.

🎯 The neutral point first

All pH electrodes are designed to deliver zero voltage at pH 7.0: a new probe gives about 0 mV there, and this voltage drifts away from zero as the probe ages. Placing the probe in this buffer therefore lets your device measure its offset and correct it for all subsequent readings. If the probe reads 7.1 in a liquid that is exactly 7.0, the device records this difference once and for all.

📐 The slope, next

The second point, at pH 4.0, serves a different purpose: it tells the meter how the probe responds in an acidic medium, in other words the slope of its measurement curve. Together with the neutral point, the slope makes readings reliable across the range that matters to you, from 6.5 to 7 for a planted tank and from 6.4 to 7.5 for an aquaponic system. Calibrating on the neutral point alone leaves that range 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 is always carried out in this order, pH 7.0 buffer first, pH 4.0 buffer second, and never the other way round. If you start with pH 4, it throws off the probe's zero, and the JBL control computer rejects it with an OFFSET message; two passes in the same pH 7 buffer, on the other hand, give a DELTAV error. So identify the bottles before opening the menu, and keep them in the same order on the table.

Replace the electrode when calibration no longer holds true

If calibration fails twice in a row with fresh buffers, the cause is rarely the solutions: it is the electrode wearing out, and its average lifespan is 24 months. The gel-electrode pH probe connects to any BNC socket and comes with its own buffers and sample cups. You are back to an accurate reading the same day, and this kit then serves for your monthly recalibrations.

🧪 The process, step by step

The full calibration takes a few minutes. Pour about 10 ml of pH 7.0 into one of the 3 test tubes supplied, dip the tip into it and confirm on your device as soon as the displayed value is stable. Then rinse the tip with distilled water and repeat the procedure with the pH 4.0 in a second test tube. Finally, discard what is left at the bottom of the test tubes rather than pouring it back into the bottles. Close all three caps straight away, because a buffer left open absorbs carbon dioxide from the air and deteriorates in turn. If your device has a temperature probe, immerse it along with the electrode: it automatically compensates for the effect of temperature on the reading.

Rinsing with distilled water determines whether the second point is valid, even though it is often seen as a minor detail. A drop of pH 7 buffer carried into the pH 4 bottle changes its value, and your meter then calculates a wrong slope without any light coming on. Tap water is not suitable for rinsing either, as it carries its own limescale and its own pH. So rinse the tip with distilled water between the two buffers, and at the end, before putting the probe back in the tank.

🗓️ Recalibration intervals

A probe should be recalibrated every 30 days, and never later than 60, because it ages continuously and each calibration compensates for that ageing. Recalibrate it also after cleaning the tip, after a long period without measurements, and whenever the reading becomes unstable. Each calibration uses 5 to 10 ml of each buffer solution: the 50 ml in a bottle therefore covers 5 to 10 recalibrations, or 5 to 10 months at the recommended rate. A dashboard that displays the countdown to the next calibration, such as the CO2 controller computer, stops you from letting the deadline slip.

In aquaponics, a probe reading drives actions that affect the fish, the bacteria and the plants all at once, such as adding bicarbonate to raise alkalinity or making a pH correction. A probe that is out by a few tenths leads you to correct water that did not need it, and since the useful range of an aquaponic system lies between pH 6.4 and 7.5, it is precisely those tenths that matter. The article on pH regulation in aquaponics details the corrections that these readings trigger.

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.

Manufacturer and product safety

Manufacturer: JBL GmbH & Co. KG
Postal address: Dieselstraße 3, 67141 Neuhofen, Allemagne
Contact: info@jbl.de
Website: www.jbl.de

Information provided under Regulation (EU) 2023/988 on general product safety.

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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

How often should you calibrate a probe?

Why pH 4 and not pH 10?

The zone that matters to you is around neutral, well away from the alkaline side. A planted tank is best kept between 6.5 and 7, an aquaponic system between 6.4 and 7.5: the pH 7 point anchors the centre of these ranges, and the slope measured between 7 and 4 keeps the reading accurate over the few tenths that separate them from it. Calibrating at pH 10 would refine a zone where you never take measurements.

Are these solutions compatible with my device?

How many calibrations do these bottles provide?

Can they be stored for a long time?

Do you really need to rinse between the two calibration points?

What if the calibration fails to validate?

The cause is almost always the probe rather than the solutions. Clean the tip with a soft cloth, then start again in order: pH 7 first, then pH 4.

On the JBL control computer, the message displayed points to the diagnosis: OFFSET indicates a probe that is too old or a calibration started with pH 4, DELTAV a slope that is too low, UNSTAB a fouled or cracked tip. If the failure keeps recurring, the electrode is at the end of its life and needs replacing.

Is this kit useful in aquaponics?

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JBL ProFlora pH calibration kit, pH 7 and pH 4 buffers

The summary