pH-down adjuster with phosphoric acid
Regular price
$13.00
Regular price
Sale price
$13.00
Unit price
/
per
| Contenance | Price | Price per L | vs 500 ml |
|---|---|---|---|
| 500 ml | $13.00 | $26.00 | — |
| 1 L | $20.00 | $20.00 | −23 % |
| 5 L | $69.00 | $13.80 | −47 % |
Plagron's pH Min is an acidic pH regulator that lowers the pH of irrigation water or a nutrient solution that is too alkaline towards the 5.5 to 6.5 range, where roots absorb nutrients in the right proportions. It is added drop by drop, once the fertiliser has been diluted.
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The summary
- Nature of the product: an acidic pH corrector, 43% P2O5, pH below 1.
- Target range: a solution pH between 5.5 and 6.5.
- Method: drip irrigation, after the fertiliser, measuring between each addition.
- Aquaponic system: never in the fish water, where pH is corrected upwards.
Bringing hard water back into the pH range where roots can feed
Plagron's pH Min is a pH down corrector based on phosphoric acid, 43% P2O5, which lowers irrigation water or a nutrient solution to between 5.5 and 6.5. Add it drop by drop after the fertiliser, measuring between additions. Corrosive, it must be handled with gloves and goggles and is never poured into an aquaponic circuit.
The pH of the water determines what the roots can actually take up from a nutrient solution. Outside the correct range, some elements become less available even though the fertiliser is there. pH Min lowers the pH of irrigation water or a hydroponic solution that is too alkaline, bringing it back into the 5.5 to 6.5 range, the one targeted by crops grown in potting compost, coco fibre and hydroponics.
This is a very concentrated acid solution, with a pH below 1, containing 43% phosphorus pentoxide soluble in water, hence its 0-43-0 analysis. Its density of 1.43 and its conductivity of 207 mS/cm give an idea of its strength: a few drops are often enough to shift the pH of a watering can. Each addition also brings a little phosphorus and slightly raises the conductivity of the solution, which is negligible at the usual doses but explains why corrections are made in small touches rather than in broad strokes.
🧪 Correcting in the right order
Dilute the fertiliser
Prepare the complete solution first, because the fertiliser itself changes the pH of the water.
Measure
Read the pH of the ready-made solution, using an electronic tester or a drop test.
Add by drip irrigation
Pour a controlled dose, pour pH Min in small amounts, stir, then measure again.
There is no fixed dose: the quantity depends on the hardness of your water and the fertiliser used. Shake the bottle, add pH Min drop by drop and stop as soon as the range of 5.5 to 6.5 is reached. An electronic pH tester makes the job quick on a hydroponic sump tank, while a drop-based pH test is enough for a few watering cans. If you overshoot the target, a pH+ corrector will bring it back up, again to be added in small amounts.
In a hydroponic sump tank, the pH is not set once and for all. It can rise from one day to the next, so you should check it every day in a stored solution. The starting pH of tap water also varies from one region to another: note how much pH Min you need for a given volume with your water, and you will save time on later preparations. Water that warms up after it has been prepared will also see its pH rise slightly.
A concentrated acid to be handled with care
pH Min contains phosphoric acid and carries the Danger warning: it causes severe skin burns and serious eye damage, it is harmful if swallowed and it corrodes metals. Wear gloves and goggles, always pour the acid into the water and never the other way round, and never mix it neat with a pH+ or a concentrated fertiliser. Measure it out with a plastic syringe, never with a metal utensil, and keep it in its original bottle, with the safety cap closed, out of reach of children and animals, between 0 and 35 °C.
Calibrate the meter before correcting
A pH correction is only as good as the reading behind it. An electronic tester drifts over time, and an error of a few tenths is enough to make you add too much acid. The pH calibration kit, with its pH 7 and pH 4 buffer solutions, recalibrates your meter in a few minutes, before each important batch of preparations.
With rainwater or very soft water, pH Min is rarely needed. These waters often have an already moderate pH and, above all, a low buffering capacity, meaning few carbonates to absorb the addition of an acid: a few drops too many will then make the pH drop sharply. Measure first, add only one drop at a time and wait a few moments between additions. It is with hard, limy tap water, rich in carbonates, that the corrector is most useful.
🌱 In aquaponics, correct upwards
In an aquaponic system, the situation is reversed. Nitrification, which converts fish ammonia into nitrates, produces acidity and uses up the water's alkalinity, so the pH of an established system tends to fall on its own. The target compromise is around 6.4 to 7.5, because nitrification slows markedly below 6 and almost stops. Correction is therefore done upwards, by alternating additions of calcium hydroxide and potassium hydroxide, or with potassium bicarbonate, while keeping an alkalinity of at least 100 mg per litre expressed as calcium carbonate.
pH Min is never poured into the fish water, neither into the tank nor into a grow bed connected to the circuit: an acid this concentrated would shift the pH far faster than the fish and bacteria can tolerate. If your tap water is very hard when the system starts up, mixing it with rainwater and the natural acidification caused by nitrification will settle the matter; the article on rainwater in aquaponics details these precautions. pH Min does, however, keep its place in a decoupled growing loop, separate from the fish, where you run the plants' solution between 5.5 and 6.5 without touching the rearing water.
📦 Sizes and storage
pH Min is available in a 500 ml bottle, a 1 litre bottle and a 5 litre container. The 500 ml bottle suits balcony watering cans and small hydroponic trays, the litre suits a tower or a family system, and the container suits greenhouses fitted with large tanks or supplied with very hard water. The product keeps for 4 years after its production date, unopened, between 0 and 35 °C, away from frost and direct sunlight. Shake it before each use and close it again immediately. Store it on its own, away from fertilisers and any metal container, and rinse off the slightest drip on the bottle with plenty of water.
Technical specifications
The product
- Type
- Acid pH correctorPhosphoric acid, NF U 42-005 standard
- Analysis
- 0-43-043% water-soluble P2O5
- pH and density
- pH below 1, 1.43 g/mlConductivity of 207 mS/cm
- Ranking
- Danger, corrosiveCauses severe skin burns and eye damage, harmful if swallowed
Use and storage
- Target range
- pH 5.5 to 6.5
- Dosage
- Drip irrigation, no fixed doseAfter the fertiliser, measuring between each addition
- Protection
- Gloves, goggles, plastic syringePour the acid into the water, never the other way round
- Storage
- 4 years sealed, from 0 to 35 °CKeep in the original sealed bottle, away from frost and sunlight
In the box
- 1 bottle or 1 container of pH Min, from 500 ml to 5 L depending on the size chosen, with a safety cap
Analysis and properties: technical data sheet of 11/03/2025; directions for use: plagron.com; hazard classification: safety data sheet of 28/11/2024 and French label.
Manufacturer and product safety
- Manufacturer
- Bertels B.V.
- Website
- plagron.com
Information provided under Regulation (EU) 2023/988 on general product safety.
Documents & manuals
pH Min data sheet
Analysis, pH, density, conductivity, directions for use and storage. Manufacturer's document, in English.
Document not showing? Some publishers block display inside a frame, so open it in a tab.
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Frequently asked questions
6 questions
6 key questions
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