Hy-pro - pH- Nitric Acid

The nitric acid version of the Hy-pro pH reducer, identifiable by the NPK 3-0-0 designation on the label. Highly concentrated and effective at minimal doses. Available up to five litres.

Hy-Pro make two bottles that are both called pH-

This is the first thing to know before ordering, and hardly any webshop states it clearly. Hy-Pro sell two pH reducers under the same name: one based on nitric acid and one on phosphoric acid. The bottles resemble each other and the product name in both cases is simply pH-.

This is the nitric acid version. You can tell from the designation under the product name on the label: NPK 3-0-0. Three percent nitrogen, no phosphorus, no potassium. A phosphoric acid product would carry a figure against the P.

That distinction is not pedantry, because the two do different things to your nutrient solution. Nitric acid leaves nitrate behind and therefore adds nitrogen. Phosphoric acid leaves phosphate behind and adds phosphorus. Which of the two you want depends on where you are in the cycle.

Why nitrogen is unhelpful in the final weeks of flowering

During vegetative growth the nitrogen this acid brings along is a small bonus that fits nicely: a stretching plant wants nitrate and you add it automatically while correcting the pH.

In the last weeks of flowering that flips. Most feed schedules deliberately taper nitrogen at that point, because a ripening plant has no further use for it and an excess keeps leaf colour dark exactly when you want to see the plant consuming its reserves. If you work on hard water and have to acidify heavily per reservoir, the nitrate contribution from your pH reducer is no longer a negligible line item.

The practical conclusion: this bottle is an excellent choice for vegetative growth and most of flowering. Anyone tapering nitrogen tightly in the final weeks while also needing a lot of acid would do better with a phosphoric or citric acid product for that period.

Measuring in the right order

Hy-Pro prescribe a fixed sequence that is worth following. Make up your water with the nutrients first. Then check the EC, because the amount of nutrient partly determines where your pH lands. Only then measure the pH, and if it is too high, mix pH- into the solution drop by drop and stir thoroughly. Measure again, and repeat until you reach your value.

Hy-Pro give 5.5 to 6.0 as the target range. More important than the exact figure is that it stays stable: if the pH swings, so does the amount of nutrient the plant can take up, and you will eventually see that in uneven growth.

Five litres and the jerrycan

This pH reducer also comes in five litres, which is why a jerrycan tap and a jerrycan opener are offered as options. With an acid, a tap is more than convenience: it lets you dose without tipping a heavy can over a reservoir, which is exactly the moment things go wrong and acid ends up on your hands or over the rim. Anyone moving up to five litres would do well to order the tap at the same time.

Available sizes

Technical Specifications:

• Type: mineral pH reducer based on nitric acid
• Manufacturer: Hy-Pro
• Label designation: NPK 3-0-0
• Adds: nitrate, so a small amount of nitrogen
• Target range: pH 5.5 to 6.0
• Application: suitable for soil, coco and hydro
• Dosage: highly concentrated, add drop by drop after mixing and measuring the nutrient solution
• Sequence: mix nutrients, check EC, then correct pH
• Storage: in a closed container at room temperature, out of reach of children
• Safety: concentrated acid, wear gloves and eye protection

Frequently asked questions

Is this the nitric or the phosphoric version?
The nitric one. The label reads NPK 3-0-0: nitrogen, no phosphorus. Hy-Pro also sell a phosphoric acid product under the same name.

Does it add nitrogen to my reservoir?
Yes, as nitrate. With small corrections that is negligible; on hard water where you dose heavily it counts.

Can I use it throughout the cycle?
For vegetative growth and most of flowering it is fine. If you taper nitrogen deliberately in the final weeks and need a lot of acid, look at a phosphoric or citric acid product for that period.

Why measure EC first and pH afterwards?
Because the nutrients shift the pH themselves. Measure pH before the feed goes in and you are correcting a value that will change again anyway.

Do I need a tap for the five litre?
Not required, but sensible. Tipping a full can of acid over a reservoir is where it goes wrong. The tap and the opener are listed as options on this product.