Bottle of Terra Aquatica liquid pH- corrector on a white background

Nutrient availability chart by pH, with the 5.5 to 6.5 target range for the pH- corrector

Liquid pH corrector pH-

8,90 €

Capacity	Price	Price per L	vs 500 ml
500 ml	8,90 €	17,80 €	—
1 L	15,90 €	15,90 €	−11 %
5 L	56,90 €	11,38 €	−36 %
10 L	96,90 €	9,69 €	−46 %
60 L	519,90 €	8,67 €	−51 %

2,96 € × 3 with no fees Klarna.

This liquid pH corrector — a blend of nitric, phosphoric and citric acids — lowers the pH of a nutrient solution and stabilises it between 5.5 and 6.5, the range at which iron, manganese and phosphorus remain available to plants. It is suitable for hydroponics, coco fibre and soil, and it is corrosive (H314).

Ref. TA-PHM-500·pH adjuster

Capacity : 500 ml

500 ml

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Delivery within 2 to 15 business days

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The summary

What it is: a liquid pH corrector based on nitric, phosphoric and citric acids, for use in hydroponics, coco fibre and soil.
Why three acids: two lower the value immediately upon addition, while citric acid maintains it over time.
How much to use: 4 ml per 50 L to start, then add in small increments while measuring.
Warning: concentrated corrosive, H314, causes severe burns to skin and eyes. Gloves and eye protection are mandatory.
Target ranges: pH 5.5 to 6.5 during growth, 6.4 to 6.8 during pre-flowering and flowering.
Sizes and dispatch: 500 ml, 1 L, 5 L, 10 L or 60 L, dispatched from France.

Nitric, phosphoric and citric acids to lower and then stabilise the pH of the solution

This liquid corrector lowers the pH of a nutrient solution and stabilises it, whether in hydroponics, on coco fibre, or in soil. pH governs the uptake of nutrients: a perfectly dosed solution left at pH 7.5 puts iron, manganese, and phosphorus out of reach of the roots, so the plant shows deficiencies even though the solution contains everything it needs.

🧬 Three combined acids

The formula combines three acids: nitric, phosphoric and citric. The first two lower the value as soon as they are added, and the effect is immediate, allowing you to take a reading as soon as the solution has been mixed. Citric acid acts as an organic buffer: it maintains the pH over time and limits the effect of excess calcium, which is particularly useful with hard water. Since nitric and phosphoric acid are also nutrients, each correction adds a small amount of nitrate nitrogen and phosphorus to your solution.

🎯 The targets and the first dose

Root development and growth

Aim for a pH of 5.5 to 6.5, the range where most nutrients remain available for uptake.

Pre-flowering and flowering

The TriPart system application chart sets the target at 6.4 to 6.8.

The first addition

Start with 4 ml per 50 L of solution, mix, measure, then add more in small increments.

The right moment

Adjust after adding the fertilisers, since each one changes the value as it dissolves.

Reading pH to one decimal place in hard water

With hard tap water, you'll need to adjust the pH each time you fill the reservoir, and often again between refills. The pocket electronic pH meter reads values to one decimal place within seconds, with temperature compensation, making repeated checks quick and straightforward. You can see exactly what each millilitre of corrector does, and note once and for all the amount your water requires.

The total quantity does not appear in any table, because it depends on the buffering capacity of your water, that is, its bicarbonate content, not on the volume being grown. Tap water often has a pH of 7 to 8, and hard water requires considerably more than rainwater to reach the same value. With a 50-litre reservoir, start with the recommended 4 ml, take a measurement, add 1 ml at a time, and note the total: as long as you use the same water and the same fertiliser, that figure will hold from one preparation to the next. Our article on pH regulation explains the method step by step.

Acid is always added to water, never the other way round

Never pour water into the acid, nor pour the neat concentrate into a tank without agitation: always add the acid to a large volume of moving water. The concentrate is at pH 1 and classified H314; it causes severe skin burns and serious eye damage: wear gloves and eye protection, and rinse thoroughly if contact occurs. Store the container upright, sealed, in its original packaging, between 5 and 30 °C and out of reach of children.

➕ What each correction does

The guaranteed analysis states 1% nitric nitrogen and 5% phosphoric anhydride. Adding 4 ml to a 50-litre reservoir, approximately 4.5 g of product, given a density of 1.12, delivers around 0.9 mg of nitrogen and 4.5 mg of phosphoric anhydride per litre. These amounts are modest compared with those of a complete fertiliser such as TriPart Grow, but they increase with your water hardness: hard water requiring ten times more corrector will deliver ten times more. In soil, the corrector works in the same way on irrigation water, which is particularly useful when your water is hard.

Technical specifications

The essentials

Function: Lowers and stabilises pHImmediate effect on the value, then pH maintenance via citric acid.
Composition: Nitric, phosphoric and citric acidsPhosphoric acid 5 to 10%, nitric acid 1 to 3%. Citric acid acts as an organic buffer.
pH of concentrate: 1Highly acidic concentrate. Never pour it neat into a tank without mixing.
Target pH range: 5.5 to 6.5During rooting and growth. At pre-flowering and flowering stages, the target shifts to 6.4 to 6.8.

Use

Appearance: Yellowish liquidThe pH+ from the same range is pale blue: no risk of mixing them up.
Compatible: Hydro, coco and soilSame product for all three growing methods. In soil, it acts on the irrigation water — useful in chalky ground — but does not have a lasting effect on soil pH.
First addition: 4 ml per 50 LThen add in small doses while measuring: the total quantity depends on your water's buffering capacity.
Relative density: 1.12One litre weighs approximately 1.12 kg.

Safety and storage

Classification: Danger, H314Causes severe skin burns and serious eye damage. Corrosive, category 1A.
Essential equipment: Gloves and gogglesPrecautionary statements P264 and P280. Wash your hands thoroughly after handling.
If swallowed: Do not induce vomitingRinse your mouth and call a Poison Control Centre (precautionary statements P301, P330 and P331).
Storage: Upright, sealed, between 5 and 30 °CIn its original packaging, away from bases and foodstuffs. Shelf life of 5 years after opening.

To budget for separately

pH measurement: Drop test kit or pH meterTo the naked eye, nothing distinguishes a solution at 6.0 from one at 7.2.
Dosing syringe: Graduated to the half-millilitreIt is used once and for all to determine the quantity your water requires.

6 further specifications are available in the detailed view.

In the box

1 bottle of liquid pH- corrector in the chosen size: 500 ml, 1 L, 5 L, 10 L or 60 L.

Classification H314, composition, pH, density, appearance and storage: French safety data sheet dated 22/11/2023. Three acids, starting dose, guaranteed analysis and shelf life: official French data sheet retrieved on 07/10/2026. pH targets: 2025 application table.

pH- or pH+: which one your water needs

Both correct the pH, but in opposite directions. The choice depends on your source water.

pH- is only needed if your pH is too high Rainwater or osmosis water requires exactly the opposite approach. Three measurements are enough to know which camp you are in.

	Effect on the solution	Water concerned	Active base	pH of concentrate	Liquid colour	Supplies phosphorus	Provides potassium	Silica source	Classified corrosive H314	Gloves and goggles must be worn	Never to be mixed with the other
Recommended pH- correctorYour choice	Lowers pH	Hard tap water	Nitric, phosphoric, citric acids	1	Yellowish	Yes	No	No	Yes	Yes	Yes
pH+ correctorYour choice	Raises pH	Reverse osmosis or rainwater	Potassium carbonate	12	Pale blue	No	Yes	Yes	Yes	Yes	Yes

pH- correctorRecommended

What each one does

Effect on the solutionLowers pH

Water concernedHard tap water

Active baseNitric, phosphoric, citric acids

pH of concentrate1

Liquid colourYellowish

What it adds on top

Supplies phosphorusYes

Provides potassiumNo

Silica sourceNo

Safety

Classified corrosive H314Yes

Gloves and goggles must be wornYes

Never to be mixed with the otherYes

pH+ corrector

What each one does

Effect on the solutionRaises pH

Water concernedReverse osmosis or rainwater

Active basePotassium carbonate

pH of concentrate12

Liquid colourPale blue

What it adds on top

Supplies phosphorusNo

Provides potassiumYes

Silica sourceYes

Safety

Classified corrosive H314Yes

Gloves and goggles must be wornYes

Never to be mixed with the otherYes

Compositions, pH values of the concentrates and classifications: French safety data sheets, version dated 22 November 2023 for pH- and 8 January 2024 for pH+. Descriptions taken from the 2025 French catalogue. Values recorded on 10 September 2026.

Documents & manuals

Safety data sheet for pH-, in French

Version dated 22 November 2023. H314 classification, declared composition, personal protective equipment, and what to do in the event of contact or ingestion.

PDF · 4

Download

Safety data sheet pH-, in English

Safety data sheet, version 8 dated 22 November 2023. Same content as the French version: H314 classification, declared composition, protection and procedure to follow. Document in English.

PDF · 4

Download

TriPart application chart, with pH targets by growth stage, multilingual document

The official TriPart system chart: target pH and conductivity ranges at each growth stage, which this corrector is used to maintain. A multilingual document, with French and English presented side by side.

PDF · 4

Download

Estimate your
delivery time

A corrosive product under CLP classification, dispatched in its original packaging by tracked parcel from France. Weight ranges from approximately 550 grams for the 500 ml to approximately 5.5 kg for the 5 L. Exact shipping costs and delivery times are shown at checkout once your address has been entered. Outside the European Union, import duties and taxes remain the responsibility of the recipient.

Frequently asked questions

6 questions

6 key questions

How much pH- is needed for 10 litres of water?

0,8 mlto start, per 10 L

4 mlto start, per 50 L

This first addition is a starting point. Mix, measure, then add further small doses until you reach the target value, as the total quantity depends on the buffering capacity of your water: rainwater responds to just a few drops, whereas hard tap water may require several times as much to achieve the same result.

Note down the amount you needed the first time — it will serve as a reliable guide for future preparations as long as the water and fertiliser remain unchanged. If you have overdone it, dilute with uncorrected water rather than adding a counteracting solution.

What pH should I aim for in my tank?

What's the difference compared to vinegar or citric acid alone?

Vinegar and citric acid are organic acids that the micro-organisms in the solution gradually break down, causing their effect on pH to fade and the water to turn cloudy.

This corrector works differently: nitric and phosphoric acids, both mineral acids, lower the value and in doing so supply nitrogen and phosphorus, while citric acid serves purely as a buffer. In a reservoir changed daily, the difference matters little; in a solution kept for two weeks, it matters considerably more.

Why is this product classified as corrosive?

The concentrate is at pH 1 and carries the hazard statement H314, causes severe skin burns and eye damage. Wear gloves and eye protection, never add water to the acid, and rinse immediately and thoroughly in the event of contact. If swallowed, do not induce vomiting.

Once diluted in a reservoir at the recommended usage quantities, there is no risk: it is the concentrate that is hazardous, not the corrected solution.

Can it be used in aquaponics, with fish?

This corrector is used differently than in hydroponics. A stocked pond cannot withstand a sudden shift in pH, and nitrifying bacteria even less so: too rapid a correction can halt biological filtration and cause ammonia levels to rise.

If lowering the pH is genuinely necessary, it should be done in very small increments over several days, with daily monitoring. Our article on pH regulation in aquaponics sets out the precautions in detail — they are quite different from those for a hydroponic reservoir.

Liquid or powder, and which size should you choose?

The liquid version acts immediately and can be dosed drop by drop, which matters when a few millilitres is the difference between 6.0 and 5.0. The powder version is a separate product in the same range: it is easier to transport and store, and its formula is considerably richer in nitrogen and phosphorus.

The 500 ml suits a small reservoir and low-hardness water.
The 1 L is the standard size, suited to moderately hard tap water.
The 5 L is for very hard water or multiple tanks, where each preparation uses noticeably more.
The 10 L and 60 L are aimed at greenhouses and commercial growers preparing several hundred litres of solution each week.

Since consumption depends on your water rather than the volume being grown, your first correction will tell you which size to choose next time.

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Liquid pH corrector pH-

The summary