Blister pack of the JBL PROAQUATEST pH refill, one reagent bottle, on a white background

JBL PROAQUATEST pH reagent refill in blister pack, seen from three-quarter view

Reagent refill for pH test, three ranges

Name: Reagent refill for pH test, three ranges
Brand: Hardy Dewerse
SKU: J2410200
Availability: InStock

$10.00

$3.33 × 3 with no fees Klarna.

This bottle is the reagent for the pH test, sold separately. Use the selector to choose the range of your test kit — 3.0 to 10.0, 6.0 to 7.6, or 7.4 to 9.0 — as it is the colour chart that interprets the result you obtain: approximately 50 readings on the wide range, 80 on the narrow range.

Ref. J2410200·Reagent refill

Model : Ph 3.0 to 10.0

pH 3.0 to 10.0

pH 6.0 to 7.6

pH 7.4 to 9.0

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The summary

What it measures: the pH, the acidity or alkalinity of your water.
What's in the box: 1 reagent bottle.
How many tests: approximately 50 on the wide range, 80 on the narrow range.
Which range to choose: the one matching your test kit, as the reagent is read against that range's colour chart.
Where and when to sample: mid-water column, always at the same point.
The test that goes with it: carbonate hardness, which determines pH stability.

The reagent bottle on its own, 50 to 80 tests depending on the range selected

pH indicates whether your water is acidic or alkaline, on a logarithmic scale where a difference of one unit represents a factor of 10 in actual acidity. This bottle is the reagent alone for the drop-based pH test, available in three ranges: the wide range from 3.0 to 10.0, and the two narrow ranges from 6.0 to 7.6 and from 7.4 to 9.0. It replaces the empty bottle in your test kit.

🎯 Three ranges, two protocols

The wide-range scale is used for orientation testing: fill a 5 ml test tube, add 5 drops, then read the colour against a white background after 5 minutes, each bottle covers approximately 50 tests. The narrow-range scales are read using two test tubes placed in a comparator block, one treated with 4 drops and the other kept with untreated water to compensate for the water's natural tint. The reading is taken after 3 minutes, and each bottle covers approximately 80 tests.

The colour chart in your kit determines the range

Order the refill for the same range as your kit, as each colour chart is printed for a single reagent and it is that reagent which converts the colour into a value. A fine-range reagent read against a wide-range colour chart, or vice versa, produces a shade with no reliable match. If you are no longer sure which range you have, check the values printed on the first and last field of your colour chart.

🌿 Fish, bacteria and plants

In a system where fish, bacteria and plants share the same water, the pH value affects all three simultaneously, yet it depends primarily on the carbonate hardness that stabilises it. For this reason, it is worth measuring both pH and KH on the same day using the carbonate hardness test, aiming for at least 5 °dKH. For a garden pond, the ideal range is between 7.5 and 8.5. The guide to adjusting pH in aquaponics explains the correct order in which to correct these two values.

Order the KH reagent alongside the pH one

If your carbonate hardness test kit is already partly used, add the KH test refill to the same order. A pH value that drops from one week to the next can only be interpreted alongside the carbonate hardness reading taken on the same day, and an empty KH bottle would leave you without that second figure. Both refills are dispatched together and store in the same box.

The reagent is classified Warning, with hazard statements H226 and H319, as it is a flammable liquid that causes serious eye irritation. For this reason, store the capped bottle in a dry place at room temperature in its original packaging, away from any source of ignition. If splashed in the eye, rinse carefully with water for several minutes, and keep the box out of reach of children despite its child-resistant cap.

🔁 The right time to replenish

The test count gives the first reference point: approximately 50 for the broad range, 80 for the narrow ranges. At the recommended rate for a new system start-up, one test per day in the first week, then one per week, the broad-range bottle therefore lasts nearly 10 months. You can also keep an eye on the drop itself: hold the bottle vertically with the tip pointing down and dry on the outside, since a drop that comes out with an air bubble will distort the dose. When the drops become irregular despite this, the bottle is nearing the end of its life and your refill takes over.

Technical specifications

What the refill contains

Contents: 1 reagent bottlepH reagent, child-resistant cap
Measurements: Approximately 50 or 8050 on the wide range, 80 on the 6.0 to 7.6 or 7.4 to 9.0 range
Water volume: 5 mlOne test tube in the wide range, two test tubes and a comparator block in the narrow range
Drops and waiting time: 5 drops, 5 min, or 4 drops, 3 minThe first protocol applies to the wide range, the second to the narrow ranges
Manufacturer's reference: JBL 2410200, 2410400, 2410600Range 3.0 to 10.0, then 6.0 to 7.6, then 7.4 to 9.0
Hazard classification: Please note, single bottleHazard statements H226 and H319. Store in a dry place, at room temperature, away from any naked flame.

To budget for separately

Test tube and colour chart: Those from the pH testThe colour chart is printed for a given range, and it is the chart that converts the colour into a value
The matching test: A carbonate hardness testAim for at least 5 °dKH to keep your pH stable

In the box

1 bottle of pH reagent, with a child-resistant cap

Reference, EAN code, contents, protocol, number of tests, and hazard statements recorded from the JBL product sheet and instructions on 07/10/2026. The 5 °dKH benchmark comes from the JBL carbonate hardness test instructions.

Estimate your
delivery time

Package weight 0.02 kg, dispatched to a collection point or to your home address, your choice at checkout. The bottle is sent in its original packaging. The exact shipping cost is shown in the basket.

Frequently asked questions

6 questions

6 key questions

Which range should I select on the dial?

Use the one from your kit, since the colour chart you have is printed for a single reagent, and it is that reagent which converts the colour obtained into a value.

Range	Use	Tests
3.0 to 10.0	General monitoring, freshwater, seawater, and pond	approx. 50
6.0 to 7.6	Precise tracking of slightly acidic or neutral freshwater	approx. 80
7.4 to 9.0	Precise tracking of seawater, a pond, or alkaline water	approx. 80

If in doubt, read the values shown on the first and last field of your colour chart.

How long should you wait before taking a reading?

Can you test water coloured by peat?

Yes, within a narrow range. The 6.0–7.6 and 7.4–9.0 refill ranges are read using two test tubes, one of which holds untreated water: placed in the comparator block, it compensates for the natural colour of the water, whether it comes from peat filtration or a treatment process.

The wide range is read using a single test tube against a white background and serves as a rough guide only. On noticeably coloured water, the reading is less reliable.

What does a logarithmic scale mean?

Where should you take the water sample for an accurate reading?

My pH drops on its own — what should I do?

Check the carbonate hardness first. Water that has almost no carbonates left can no longer neutralise the acids produced by life in the tank, and its pH drops without any action on your part.

Correcting the pH in water with no buffering reserve is only ever a temporary fix. Raise the alkalinity to at least 5 °dKH, allow the water to stabilise for 24 hours, then repeat this measurement: the pH will often have stabilised on its own.

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Reagent refill for pH test, three ranges

The summary