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-

$11.00

Capacity	Price	Price per L	vs 500 ml
500 ml	$11.00	$22.00	—
1 L	$19.00	$19.00	−14 %
5 L	$66.00	$13.20	−40 %
10 L	$111.00	$11.10	−50 %
60 L	$595.00	$9.92	−55 %

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

The liquid pH- corrector is a blend of nitric, phosphoric and citric acids that lowers the pH of a nutrient solution, in hydroponics, on coco fibre and in soil. The first two act as soon as they are added, while the citric acid holds the value. Start with 4 ml per 50 L, then measure and adjust.

This liquid corrector lowers the pH of a nutrient solution and stabilises it, in hydroponics, on coco fibre and in soil. pH governs the uptake of nutrients: a perfectly dosed solution that has remained at pH 7.5 leaves 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, so you can measure as soon as the solution is mixed. The citric acid acts as an organic buffer: it holds the pH over time and limits the effect of excess calcium, which is mainly useful with hard water. As nitric acid and phosphoric acid are also nutrients, each correction adds a little 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

On hard mains water, you correct every time you prepare a reservoir, and often with a top-up adjustment in between. The AMTRA electronic pH tester shows the value to the hundredth, with an accuracy of 0.05, within a few seconds, with temperature compensation, which makes these repeated checks quick. You can see exactly what each millilitre added does, and you note down once and for all the amount your water needs.

The total quantity cannot be read from any table, because it depends on the buffering capacity of your water, that is, its bicarbonate content, and not on the volume being grown. Tap water often has a pH of 7 to 8, and hard water needs noticeably more than rainwater to reach the same value. For a 50-litre reservoir, start with the recommended 4 ml, measure, add 1 ml at a time, and note the total: as long as you keep the same water and the same fertiliser, that figure remains valid from one batch to the next. The article on maintaining a hydroponic system describes the same approach of small successive adjustments, stirring as you go.

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

Never pour water into acid, nor the neat concentrate into a reservoir without stirring: pour the acid into a large volume of moving water. The concentrate is at pH 1 and classified H314, causing severe skin burns and serious eye damage: wear gloves and goggles, and rinse thoroughly in case of contact. Store the container upright, closed, in its original packaging, between 5 and 30 °C and out of reach of children.

➕ What each correction does

The guaranteed analysis states 1% nitrate nitrogen and 5% phosphorus pentoxide. For an addition of 4 ml to a 50-litre reservoir, or about 4.5 g of product given its density of 1.12, you therefore supply close to 0.9 mg of nitrogen and 4.5 mg of phosphorus pentoxide per litre. These amounts remain small compared with those of a complete fertiliser such as TriPart Grow, but they increase with the hardness of your water, and a very hard water that calls for ten times more corrector supplies ten times as much. In soil, the corrector acts in the same way on the irrigation water, which is mainly 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.

Manufacturer and product safety

Manufacturer: TERRA AQUATICA (SAS, SIREN 840329619), ex General Hydroponics Europe
Postal address: 4 boulevard du Biopole, ZI du Biopole, 32500 Fleurance, France
Contact: info@terraaquatica.com ; +33 5 62 06 08 30
Website: www.terraaquatica.com

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

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 with, per 10 L

4 mlto start with, per 50 L

This first addition is a starting point. Mix, measure, then top up in small doses until you reach the target value, because the total amount depends on the buffering capacity of your water: rainwater reacts to a few drops, whereas hard mains water may need several times more for the same result.

Note down the amount you needed the first time; it will hold for later batches as long as the water and the fertiliser do not change. If you have overshot, dilute with uncorrected water rather than adding a reverse corrector.

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, which the micro-organisms in the solution gradually break down, so that their effect on pH fades and the water can turn cloudy.

This corrector works differently: nitric and phosphoric acids, which are mineral acids, lower the value and supply nitrogen and phosphorus along the way, while citric acid serves only as a buffer. In a reservoir that is renewed every day, the difference matters little; in a solution kept for two weeks, it matters 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 serious eye damage. Wear gloves and goggles, never pour water into the acid, and rinse immediately and thoroughly in case of contact. If swallowed, do not induce vomiting.

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

Can it be used in aquaponics, with fish?

The corrector is used differently from in hydroponics. A stocked pond cannot tolerate a sudden change in pH, and the nitrifying bacteria even less so: a correction that is too rapid can halt biological filtration and cause the ammonia level to rise.

If a reduction is truly necessary, it should be done in very small amounts, over several days, with a daily check. The article on pH regulation in aquaponics details the precautions, which have nothing to do with those for a hydroponic reservoir.

Liquid or powder, and which size should you choose?

The liquid, this one, acts immediately and can be dosed drop by drop, which matters when a few millilitres separate 6.0 from 5.0. The powder version is a different product from 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 water that is not very hard.
The 1 L is the usual size, suited to moderately hard tap water.
The 5 L is for very hard water or several tanks, where each batch uses considerably more.
The 10 L and the 60 L are for greenhouses and growers who prepare several hundred litres of solution every week.

Since consumption depends on the water and not on the volume grown, your first correction will tell you which size to buy next.

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Liquid pH corrector pH-

The summary