Canna - pH- Pro Grow

A highly concentrated mineral pH reducer from CANNA for the vegetative phase, based on 17% hydrochloric acid and 3% nitric acid. Roughly 0.5 ml per 10 litres of nutrient solution.

This acid was chosen for what it does not add

A pH reducer is never only an acid. Whatever you pour into the reservoir stays there, and the anion of that acid is almost always a plant nutrient. Phosphoric acid leaves phosphate behind, nitric acid leaves nitrate behind. At a few millilitres per hundred litres that hardly registers, but once you are acidifying a reservoir of hard water the contribution climbs to something your feed schedule has to account for.

That is why CANNA sells two different acids for two phases. The flowering version is 59% phosphoric acid, and that phosphate load is welcome in bloom. In vegetative growth you specifically do not want it: a plant that is stretching needs nitrogen and potassium, not extra phosphate. So this grow version does most of its acidifying with hydrochloric acid, which leaves chloride behind, and chloride is not a macro element your schedule budgets for. The small 3% share of nitric acid contributes a modest amount of nitrate.

That is the entire reason this bottle exists alongside the bloom one. It is not a nitrogen feed in disguise and should not be treated as one: at 3% nitric against 17% hydrochloric, the nitrogen contribution is incidental. The point is that you can correct pH without shifting your ratios.

Check which bottle you are buying, Pro is not the same as standard

Alongside this Pro version CANNA also sells an ordinary pH- Grow, and that one is 38% nitric acid. Different product, different composition, while the names differ by a single word and the bottles are hard to tell apart in a photograph. This page is the Pro. If you are used to the standard version, note that it acidifies with nitrate and this one largely with chloride, so the dosing and the effect on your solution are not identical.

Dosing without overshooting

Mix your nutrients first and check the EC. Only then measure pH and correct, because the feed itself moves the pH as well. CANNA gives roughly 0.5 ml per 10 litres as a guideline, but that is a starting point rather than a recipe: how much you need depends on the hardness of your tap water and on how much nutrient is in the tank. Hard water buffers and asks for noticeably more, reverse osmosis water asks for almost nothing.

Add in small steps, stir the reservoir thoroughly and measure again. Give it a moment before you judge the result. Anyone who tips in a generous splash at once undershoots, corrects with pH+, and ends up with a reservoir containing both acid and base and an EC higher than intended. Coming back up always costs more than approaching carefully.

The safety notes are not a formality here

This is concentrated hydrochloric acid. It causes severe burns and eye damage and the vapour can irritate your airways. Wear gloves and goggles, work in a ventilated space, keep the bottle hermetically sealed and store it in its original packaging out of reach of children. Always pour the acid into the water, never the other way round.

Technical Specifications:

• Type: mineral pH reducer, liquid concentrate
• Manufacturer: CANNA
• Composition: 17% (m/m) hydrochloric acid (HCl), 3% nitric acid (HNO3)
• Phase: vegetative
• Dosage: approximately 0.5 ml per 10 litres of nutrient solution
• Recommended pH: 5.2 to 6.2 depending on substrate
• Volume: 1 litre
• Storage: hermetically sealed, in the original packaging, 10 to 30 °C, protected from heat, frost and direct sunlight
• Hazards: harmful if swallowed, causes severe skin burns and eye damage, may cause respiratory irritation

Frequently asked questions

Why a separate bottle for grow and bloom?
Because the acid itself leaves something behind. The bloom version adds phosphate, which suits flowering and does not suit vegetative growth. This one acidifies mainly with chloride and barely shifts your ratios.

Is this the same as CANNA pH- Grow?
No. The standard pH- Grow is 38% nitric acid, this Pro version is 17% hydrochloric with 3% nitric. Different composition, different dosing.

Can I use it in flowering too?
Yes, and in one case CANNA recommend it. If you run CANNA PK 13/14, the phosphoric bloom version can cause saturation in the tank; CANNA then advise this bottle, because nitric acid brings no phosphate with it. Otherwise CANNA's own classification stays vegetative.

Can I mix this into my nutrient bottle?
No. Always add it to the made-up reservoir, never undiluted into a concentrated fertiliser.

How much do I need per reservoir?
It varies with your tap water. Hard water buffers strongly and needs noticeably more than reverse osmosis water. Measuring is the only way; there is no fixed dose.