Canna Calmag Agent - Corrects Soft or RO Water Before You Feed
Best for: Growers using soft tap water or reverse-osmosis water who need to add back the calcium and magnesium their base nutrients expect.
Our thoughts
You can dose your main nutrients perfectly and still end up with a deficiency if your water's the problem, not your feed. If you're on soft mains water or running RO, Calmag Agent fixes that before it ever becomes an issue.
CANNA Calmag Agent is a concentrated calcium and magnesium supplement, formulated to a 3:1 calcium-to-magnesium ratio, designed to correct water that's naturally low in minerals - soft tap water, or water that's been through a reverse-osmosis filter. Without enough calcium and magnesium in the water itself, plants can come up short on both regardless of how correctly you're dosing your main nutrient line.
CANNA's own Coco and Terra nutrient ranges are designed to work best with water at an EC of around 0.4-0.5 mS/cm, which is where Calmag Agent's dosing guidance is aimed.
How it compares
Cal-Mag supplements all solve the same underlying problem, with slightly different dosing approaches.
- BioBizz's Cal-Mag addresses the same soft-water or RO-water calcium and magnesium shortfall for growers on their nutrient range
- Advanced Nutrients' Cal-Mag Xtra follows a similar principle of correcting water mineral content before feeding
- CANNA Calmag Agent ties its dosing to a specific target EC (around 0.4mS/cm) rather than a generic "add this much" instruction, which makes it easier to dose accurately for your actual water
All of these products are solving a water-quality problem rather than a feeding problem, so pick the one that matches the nutrient line you're already running.
Usage guidance
Getting the dosing right starts with knowing your water.
Testing your water
Check the EC of your source water first. Soft water reads below 0.4 mS/cm, while normal water sits between 0.4 and 0.5.
Dosing
Add 0.1-0.5ml per litre of Calmag Agent until your water reaches an EC of around 0.4mS/cm, then dose your normal nutrients and additives on top of that.
Ongoing use
Retest periodically, as water hardness can shift through the year in some areas, especially where supply sources change seasonally.
Technical specifications
- Type: Calcium and magnesium water conditioner
- Ca:Mg ratio: 3:1
- Target: Raises soft or RO water to approx. 0.4mS/cm EC
- Dosage: 0.1-0.5ml per litre
- Pack sizes: 1L, 5L and 10L
- Suitable media: All growing media
- Brand: CANNA
Who this is for
- Growers in soft water areas
- Growers using RO-filtered water
- Anyone seeing calcium or magnesium deficiency symptoms despite correct base feeding
Worth testing your water before you assume a deficiency is a feeding problem rather than a water one.
Our take
Water quality is one of the most overlooked variables in a grow, and this fixes it at the source rather than leaving you to chase deficiency symptoms that were never a feeding issue to begin with.
One we sell a lot of for new growers working out why their feed "isn't working."
