Canna CalMag Agent

Canna CalMag Agent

Regular price £13.45
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Canna CalMag Agent

To ensure an optimal mineral balance regardless of your quality of water, CANNA CALMAG AGENT provides a highly concentrated solution of calcium and magnesium, at the ideal ratio, for exceptional plant growth. Perfect for correcting water sources of varying hardnesses, CALMAG AGENT ensures consistently strong and healthy plant growth.



  • Ideal 3:1 Ca to Mg ratio
  • Highly concentrated
  • Improves poor-quality water
  • Improves nutrient uptake
  • Stronger, healthier plants
  • Reduces susceptibility to deficiency/disease

Water Hardness

The properties of water in the UK vary from region to region. CANNA's TERRA and COCO nutrients are most compatible with normal water, typically with an EC of 0.4-0.5.

What is the difference between soft/hard and/or bad water and what can you do about it?

Soft water has an EC level of below 0.4. With CANNA CALMAG AGENT you can raise your EC level to 0.4.

Normal water has an EC level between 0.4 and 0.5. It contains calcium, magnesium and bicarbonate to stabilise the pH. CANNA TERRA and COCO base nutrients are designed to work best with this type of water.

Hard water (EC>0.5) contains more calcium and magnesium than the plant can handle. When you’re growing plants, the best way to treat this kind of water is to use a reverse osmosis filter and then mix your hard water with the R.O. water, until you reach an EC level of 0.4.

Bad water (EC>0.5) contains mostly sodium and chloride. These two elements can block the uptake of beneficial nutrients and become toxic to your plants. With a Reverse Osmosis (R.O) filter, you can remove both of these elements. Simply making a mixture of bad water and R.O water to an E.C of 0.4 will result adequate bi-carbonates to stabilise pH levels, but the calcium and magnesium levels will be too low. Make a mixture of R.O and tap-water until you reach an E.C of 0.2 and then add CANNA CALMAG AGENT until you reach an E.C of 0.4.


What's in the box?

1 x Canna CalMag Agent (1L, 5L)

We also have 10L available on request.


Don't see the product/size/information you're looking for? Please feel free to contact us with any specific product queries and we'll be happy to help.


User Instructions (Soft Water)

  • Shake well before use
  • Fill nutrient reservoir with water (20-22°C).
  • Add 0.1-0.5 ml per litre CANNA CALMAG AGENT until you reach an EC of 0.4mS/cm. On top of this water you use the normal recommended nutrients and additives

Storage, health and other directions

  • Keep bottles sealed air-tight.
  • Keep only in the original container.
  • Protect from heat, frost and direct sunlight.
  • Recommended storage temperature 10 - 30 °C.

CANNA only works with high graded nutrients and chelates, which are immediately and completely available for the plant. The bottle is made of polyethylene (PVC and cadmium free), a recyclable plastic


Click any of the links below for the relevant feed chart:






We aim to dispatch all orders made before 2PM the Same day. This excludes weekends and bank holidays.

All items are sent in plain secure packaging with no logos. Once dispatched you will receive tracking information. Average delivery time is 1-2 days after dispatch for UK customers. Please contact us if your order hasn't arrived within 5 working days from payment for UK customers and 7 working days for EU customers.

Mainland UK - Delivery is free when you spend over £65. Or £6.95 if the total order value is under £65. All orders are sent on next day working day delivery via DHL. 

NI/Scottish highland/Other non standard postcodes - Delivery is £12.95 All orders are sent on 48H delivery via DHl


We will replace any item that arrives damaged.

If your product arrives damaged. Please contact us immediately to claim a replacement.

A limited replacement warranty is offered on all our products. Please check the product listing for the exact warranty time given. If your unit becomes faulty please return it to us for a replacement.

Replacements will only be given once the faulty unit has been inspected.

Warranties are not given due to customer misuse. If we find your return to be in working order, or damaged due to misuse it will be returned to you and no replacement offered.

Proof of purchase must be shown.



We offer a 30 day cancellation policy. A 20% restocking fee will be applied to your order. Refunds can take up to 5 working days to process. 

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