Box of pH drop test, range 3.0 to 10.0, 50 tests stated on the packaging

pH test kit photographed by the manufacturer: graduated test tube, syringe, reagent bottle and 14-colour comparison chart

Dropper bottle of pH reagent, labelled pH 3-10, child-resistant cap

Adding the reagent to the test tube placed on the colour chart, then reading the colour result for the pH test

Graph: water acidity is multiplied by ten for each unit drop in pH, from pH 9.0 to pH 6.0

pH drop test kit

Name: pH drop test kit
Brand: Hardy Dewerse
Price: 1800.0 JPY
Availability: InStock

¥1,800

¥600 × 3 with no fees Klarna.

This test gives the pH from 3.0 to 10.0 by colour reading, in fresh water, in ponds and in aquaponics.

The reading should be taken alongside the carbonate hardness, or KH, which stabilises the pH, and with the time of measurement in mind, since the pH of a planted tank varies throughout the day.

Water test

Customer support 7 days a week by email

Delivery within 2 to 15 business days

100 % secure payment

The summary

What you receive: one reagent bottle, a graduated plastic test tube and a 14-colour chart, for approximately 50 tests.
What you measure: pH from 3.0 to 10.0 across 14 colour fields, in freshwater, saltwater and garden pond water.
What the figure means: the scale is logarithmic. Between pH 7.5 and pH 8.5, your water becomes ten times more alkaline.
When to test: always at the same time of day, and make a note of it. In a planted tank, pH can shift by several tenths between morning and evening.
How to choose: this is the wide-range version, designed for screening rather than fine adjustment.
What we send you: a parcel weighing 0.12 kg, reagent in its original packaging.

Wide-range drop test, from 3.0 to 10.0, for aquarium, pond and aquaponics

pH is the parameter you will measure most frequently, and its value should always be interpreted alongside other readings. This test gives a figure between 3.0 and 10.0, which on its own says nothing about whether your water is stable or will remain so, since that stability depends on carbonate hardness. A correction made on the basis of pH alone can therefore cause a sharper swing than the imbalance it was intended to address.

📉 A logarithmic scale

pH is a logarithmic scale: each unit represents a factor of 10. Water at pH 7.5 is 10 times less alkaline than water at pH 8.5, and a difference of 0.5 already represents a ratio of 3. This is why a pH that shifts by one unit in a single evening puts your fish under serious stress, whereas the same change spread over 3 weeks is far better tolerated: it is sudden swings that must be avoided above all else. The article on pH regulation explains the procedure in detail.

In aquaponics, a trade-off

Nitrification is most efficient between 7 and 8, whilst roots absorb iron and phosphorus more readily below 7, so the usual compromise sits around 6.8.

In a garden pond

The favourable range is between pH 7.5 and 8.5. A step of 0.5 is enough to push the value outside this range.

In very soft water

Without a buffer, pH drops on its own, sometimes below 6, where narrow colour charts run out.

After adding

pH corrector, fresh grow medium, limestone, peat: each one changes the value, not always in the expected direction.

Measure KH before correcting pH

What stabilises pH is carbonate hardness, which absorbs the acids produced by nitrification. Take the carbonate hardness test alongside this one: if KH is high, a pH corrected with an adjuster will return to its equilibrium value within a few days; if it's low, there's no buffering capacity left and pH can crash suddenly. With both figures to hand, you'll know which one to correct and in what order.

🕑 The time of the reading

In a planted volume, dissolved carbon dioxide causes the pH to vary from hour to hour: during the day photosynthesis consumes it and pH rises, while at night plants and bacteria release it and pH falls. The swing commonly reaches several tenths of a unit between early morning and the end of the day. Always measure at the same time of day and make a note of it; to establish the true range of your system, take two readings on the same day rather than two readings a week apart.

Three mistakes that skew pH readings

Read the result in daylight, with the test tube resting on a white background, as aquarium lighting distorts the perception of yellows and greens. Use exactly 5 ml and 5 drops, the number of drops is calibrated for that volume alone, and wait the full 5 minutes before comparing. Always take your sample from the middle of the water column, never directly beneath the surface film.

🐠 pH and ammonium toxicity

pH also determines the toxicity of ammonium. Dissolved ammoniacal nitrogen is divided between the ammonium ion, which is relatively harmless, and ammonia, which crosses the gill membranes; the proportion of ammonia increases with pH. At 25 °C, it accounts for around 0.6% of ammoniacal nitrogen at pH 7, compared with 5.4% at pH 8: the same ammonium level is therefore nearly 10 times more dangerous in a pond at pH 8 than in a tank at pH 7. Always read your ammonium test alongside the pH recorded on the same day, especially in summer, when temperature compounds the effect of pH.

Technical specifications

The essentials

Parameter measured: pH, acidity or alkalinity of the waterLogarithmic scale: a difference of one unit equals a factor of ten in actual acidity
Measurement range: 3.0 to 10.0This is the wide-range version in the range. Two finer versions cover 6.0 to 7.6 and 7.4 to 9.0.
The colour chart fields: 14 colours, from 3.0 to 10.0One field at 3.0, then steps of 0.5 from 4.0 to 10.0. Match between two adjacent fields. A difference of 0.2 units cannot be read here
Tests per kit: Approximately 50
Method: Liquid reagent, colorimetric readingA single sample, with no reference: this test does not use a comparator block
Manufacturer's reference: JBL 2410100, PROAQUATEST rangeCode EAN 4014162241016

The procedure

Water volume: 5 mlSamples taken from mid-column, never just below the surface
The steps: Rinse, fill, dose, shake, wait, readThe number of drops is calibrated for this volume and no other
Waiting time: 5 minutesStabilisation time. An immediate reading gives a shade that is still changing.
Total duration: Approximately 6 minutesHandling included
Reading: Colour chart, in daylightAquarium lighting skews the perception of yellows and greens, and therefore the reading obtained
Environments covered: Freshwater, saltwater, pondThe wide range is suited to screening rather than fine-tuning a reef tank

Security and parcels

Ranking: WarningThe lower of the two threshold levels under CLP regulations
Main risks: Flammable, causes serious eye irritationH226 and H319 statements
Precautions: Rinse the eye with water, keep out of reachAdvice P101, P102, P305 with P351 and P338. Keep away from all sources of ignition.
Parcel weight: 0.12 kgPackaging included

To budget for separately

The matching test: A carbonate hardness testIt shows whether your pH will remain stable, and it is the first thing to correct
Reagent refill: Reagent only, ref. 2410200The test tube and colour chart keep well

10 further specifications are available in the detailed view.

In the box

1 bottle of pH reagent with child-safety cap
1 graduated plastic test tube
1 14-field colour chart, from 3.0 to 10.0
1 multilingual instruction leaflet, French included

Reference, EAN code, kit contents, range, reading increment, protocol, and hazard information taken from the manufacturer's data sheet and instructions on 05/09/2026. The number of tests is that printed on the packaging. The daily pH swing in a planted tank is an approximate figure; it depends on the plant mass and the lighting.

pH alone, or all the water chemistry?

pH should never be interpreted without carbonate hardness. First check whether the column gives you both values, then what it covers around them.

A fluctuating pH should be interpreted alongside KH pH is a result: it drops when KH is exhausted, and rises when plants consume CO2. Depending on the age of your tank, you may need the figure alone or also the values it depends on.

	Parameters covered (parameters)	Drop tests included (tests)	pH	KH, the carbonate hardness that stabilises pH	Ammonium, nitrites and nitrates	GH, iron, phosphates, copper, silicates, oxygen	Reagent bottles (bottles)	Glass test tubes	Laboratory comparator block	Thermometer	Reagent refill sold separately	Price
Recommended pH test only, wide rangeYour choice	1 parameters	1 tests	Yes	No	No	No	1 bottles	0	No	No	Yes	¥1,800
6-in-1 Aquarium Water Testing KitYour choice	6 parameters	5 tests	Yes	Yes	Yes	No	9 bottles	3	Yes	No	Yes	¥9,300
14-in-1 water analysis kit for aquariumYour choice	14 parameters	13 tests	Yes	Yes	Yes	Yes	23 bottles	12	Yes	Yes	Yes	¥21,700

pH test only, wide rangeRecommended

What you're measuring

Parameters covered (parameters)1 parameters

Drop tests included (tests)1 tests

pHYes

KH, the carbonate hardness that stabilises pHNo

Ammonium, nitrites and nitratesNo

GH, iron, phosphates, copper, silicates, oxygenNo

Equipment supplied

Reagent bottles (bottles)1 bottles

Glass test tubes0

Laboratory comparator blockNo

ThermometerNo

Budget

Reagent refill sold separatelyYes

6-in-1 Aquarium Water Testing Kit

What you're measuring

Parameters covered (parameters)6 parameters

Drop tests included (tests)5 tests

pHYes

KH, the carbonate hardness that stabilises pHYes

Ammonium, nitrites and nitratesYes

GH, iron, phosphates, copper, silicates, oxygenNo

Equipment supplied

Reagent bottles (bottles)9 bottles

Glass test tubes3

Laboratory comparator blockYes

ThermometerNo

Budget

Reagent refill sold separatelyYes

14-in-1 water analysis kit for aquarium

What you're measuring

Parameters covered (parameters)14 parameters

Drop tests included (tests)13 tests

pHYes

KH, the carbonate hardness that stabilises pHYes

Ammonium, nitrites and nitratesYes

GH, iron, phosphates, copper, silicates, oxygenYes

Equipment supplied

Reagent bottles (bottles)23 bottles

Glass test tubes12

Laboratory comparator blockYes

ThermometerYes

Budget

Reagent refill sold separatelyYes

Parameters covered, equipment supplied and kit contents noted from the three product pages on 05/09/2026.

Documents & manuals

Official manufacturer's instructions

Full broad-range pH test protocol, volumes and number of drops, hazard statements and precautionary advice. Document published by the manufacturer, multilingual, French included.

PDF · PDF

Download

Estimate your
delivery time

Package weight 0.12 kg, dispatched to a collection point or by Colissimo home delivery, your choice at checkout. The reagent is sent in its original box with a child-resistant cap. The exact amount is shown in the basket.

Frequently asked questions

6 questions

6 key questions

What pH should you aim for in aquaponics?

Why is my pH different in the morning than in the evening?

The cause is carbon dioxide. During the day, photosynthesis consumes it and the pH rises; at night, plants and bacteria release it and it falls. In a well-planted tank, the swing commonly reaches several tenths of a unit.

This is the normal behaviour of your system. The only rule that matters is to measure at the same time every day, otherwise you are comparing two different bodies of water.

My pH rises again after every water change — why?

This test ranges from 3.0 to 10.0 — isn't that too broad?

Drops or electronic pH meter?

My test always gives the same colour — is it no longer usable?

Check the volume collected: the dosing is calibrated for 5 ml only.
Count the drops aloud — a missed drop will throw off the colour reading.
Read the result in daylight, never in front of the tank.
Test your tap water: if it gives a different result, the reagent is working correctly.

A pH that is genuinely stable from one week to the next simply indicates well-buffered water.

Let us talk about your project

A question about this product or your setup? Our team will answer and advise you.

Email us Contact form

Interest-free instalment payments

Offered depending on the cart amount, at checkout.

Delivery in 2 to 15 working days

Depending on the products and shipping sites. Estimate by destination in the estimator on this page.

After-sales service 7 days a week by email or chat

Our team answers all your questions.

Shop responsibly

Become part of the change.

pH drop test kit

The summary