Plagron - pH Min

A mineral pH reducer based on phosphoric acid, which Plagron registers as a fertiliser under the designation NPK 0-43-0. Dose drop by drop until you land in the 5.5 to 6.5 range.

This is officially a fertiliser, and that is not a formality

On the label and on the technical data sheet, pH Min is registered as an NPK fertiliser 0-43-0, with 43% water-soluble phosphorus pentoxide. That is neither marketing nor a footnote: it means the regulator treats this product as a feed, because in substance it is one. Every millilitre you add delivers phosphate.

Plagron themselves draw a conclusion from that which you will rarely see stated elsewhere. Their own FAQ asks whether you can use pH Min to correct an excess of pH Plus. The answer is that it works, but that it alters the NPK value of your fertilisers, and that they therefore advise against it. Put differently: correcting back and forth between acid and base is not free. Every correction adds both phosphate and potassium to a reservoir whose EC is quietly climbing.

The practical rule that follows: always approach your target from above and in small steps. Five doses of a few drops beat one overshoot followed by a walk back.

What Plagron's own figures tell you

The technical data sheet gives a handful of numbers that turn out to be surprisingly useful once you set them side by side. The pH of the concentrate is below 1, so low that Plagron notes it cannot be measured accurately. Conductivity is 207 mS per centimetre. For comparison, a made-up nutrient solution typically sits around 1.5 to 2.5 mS per centimetre.

That two-orders-of-magnitude gap is exactly why you dose this by the drop and not by the measuring jug. Density is 1.43 grams per millilitre, meaning a litre weighs over fourteen hundred grams: a bottle heavier than it looks, and one to transport upright. The liquid itself is clear, colourless, odourless and does not foam.

Why there is no fixed dose

Plagron answer that question themselves, and the answer is worth repeating: how much pH Min you need depends on your water quality and on how much nutrient you are using. Both change, so the amount required changes with them. That is why a pH meter or pH strips are part of the kit, and why the bottle carries an instruction to add drop by drop rather than a number.

Shake before use. Mix your nutrients first, check the EC, and only then correct the pH, because the feed shifts acidity by itself. Measure after every addition.

Available sizes

Technical Specifications:

• Type: mineral pH reducer based on phosphoric acid
• Manufacturer: Plagron
• Registration: NPK fertiliser 0-43-0
• Phosphorus pentoxide (P2O5): 43%, water soluble
• Acidity of the concentrate: pH below 1, too low to measure accurately
• Conductivity of the concentrate: 207 mS/cm
• Density: 1.43 g/ml
• Appearance: clear, colourless and odourless liquid, no foaming
• Target range: pH 5.5 to 6.5
• Application: suitable for all watering systems, vegetative and flowering phase
• Dosage: shake well, then add drop by drop and keep measuring
• Storage and transport: between 0 and 35 °C, frost-free and out of direct sunlight
• Shelf life: 4 years from production, unopened

Frequently asked questions

Why is there no fixed dose on the bottle?
Because there is not one. How much you need depends on your water quality and on how much nutrient is in the reservoir, and both change from mix to mix. A pH meter or pH strips are not a luxury here.

Can I use it to correct an excess of pH Plus?
It works, but Plagron advise against it because it changes the NPK value of your fertilisers. Better to approach your target from above in small steps so you never have to come back.

Does the phosphate from this bottle count as feeding?
In principle yes, the product is registered as NPK 0-43-0. On soft water with normal corrections the contribution is small; on hard water where you dose heavily it becomes noticeable.

Can I use it during vegetative growth?
Yes, Plagron state the product can be used in both the vegetative and flowering phase and suits all watering systems.

How long does an unopened bottle keep?
Four years from the production date. Store and transport it between 0 and 35 degrees, frost-free and out of the sun.