Skip to main content
Free Delivery Over $499*
Discreet Shipping
3000+ Products
140K+ Orders Dispatched

Canna Calmag Agent - 1L / 5L | Calcium & Magnesium Supplement

Perfected for use on Canna Coco Professional substrate

SKU: ADDT20500




$53.96 WAS $59.95

$59.95 per 1L


Save 28%!

Sale Ends in 31 May 2024

With varying water quality throughout Australia and New Zealand and more and more people using Reversed Osmosis water on COCO substrates, we have created thé solution to your soft water problems: CANNA CALMAG AGENT.

Pick up at store Free

Delivery Options:

If cart total is less than $499*

Freight applies

If cart total is $499* & above


*excluding bulky items

International shipping

Click here



Pay in 4, interest-free. Afterpay it.


Repay on a convenient weekly, fortnightly or monthly schedule.


There is a complex chemistry in your water going on when using soft water or Reverse Osmosis (RO) water in combination with a Coco substrate within the divalent ions such as Calcium and Magnesium. By addressing this issue appropriately, one can manage any problems while avoiding the over-application of calcium. Over-application can decrease the availability of certain nutrients, such as potassium, to the plant. 

Due to variations in tap water quality across Australia and New Zealand, we developed CANNA CALMAG AGENT to condition and stabilize the pH of coco substrates. Our product ensures a balanced addition of calcium and magnesium through nutrients specially designed for this purpose. It will increase the electrical conductivity (EC) of the water used, stabilizing the water available for plant uptake. This harder water creates an optimal base for plants to absorb all necessary nutrients for healthy, strong growth in a coco substrate. 

In The Box

  • [1] x Canna Calmag Agent - 1L / 5L

Benefits of CANNA CALMAG AGENT include:

  • Tailored for CANNA coco substrates
  • pH stabilization of water 
  • Reduced deficiencies of calcium and magnesium
  • Enhanced nutrient uptake
  • Stronger plant growth
  • Stimulation of higher-quality flowers
  • Increased water EC

On soft or RO water

  1. Mix your desired nutrients in the tank first
  2. Mix in the additives to be used such as CANNABOOST, RHIZOTONIC, CANNAZYM and, or PK13/14
  3. Add CANNA CALMAG to the nutrient mix last following these guidelines:
  4. Dosage: Depending on water quality, softness and target plant, use 5 - 10 ml / 10 litres.
  5. Keep in mind that a stable pH is also temperature-dependent.
  6. The nutrient solution can be applied directly after mixing but wait 24-48 hours before doing any pH adjustment to allow correct buffering of your solution.


  • Be careful when using a pH Up (+) as CANNA CALMAG AGENT will first drop in pH and rise over the course of the next 24–48 hours

For more information about water quality and when to use CANNA CALMAG Agent, see the CALMAG articles on the CANNA website.

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

We have divided water into four different types:

  1. soft water
  2. normal water
  3. hard water
  4. bad water

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 0.7. It contains calcium, magnesium and bicarbonate to stabilize the pH. All CANNA products are designed to work best with this type of water.

Hard water (EC>0.8) 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. Or, more easily, you can use 100% R.O. water and then use CANNA CALMAG AGENT to raise your EC level to 0.4.

Bad water (EC>0.8) contains mainly sodium and chloride. These two elements block the uptake of nutrients and can even become toxic to your plants. With a reverse osmosis filter, you can remove both these elements. But making a mixture of R.O. water and bad water will not bring in enough calcium and magnesium, only bicarbonate to stabilize the pH. Make a mixture of R.O water with the bad water until you reach an EC of 0.2 and then add CANNA CALMAG AGENT to this water until you reach an EC level of 0.4, or use 100% R.O. water in combination with CANNA CALMAG AGENT until you reach EC level 0.4

How can you test the difference between hard water and bad water?

The easiest and best way to find out, is to contact your local water supplier. They should be able to provide you with an overview of the ions in your tap water. An other option is to have your water analyzed by an official laboratory.

You can also test the water yourself using an EC meter and 2 small tests based on color indication. First, measure the EC to be sure it is not SOFT or NORMAL water:

  • EC 0.0–0.3: the water is Soft
  • EC 0.4–0.7: the water is Normal

If the EC >0.8, continue with the test (to determine which elements contribute to the EC measured).

  • A testing kit can be bought in an aquatic shop.
  • Buy the kH and the gH bottles.
  • If the gH (Gesamthärte = general hardness) < 8 (drops), the water is BAD, e.g. the EC consists mainly of sodium, chloride etc. not calcium and/or magnesium.

If the gH is > 8 continue with the TEST.

  • kH (Carbonat-Härte = carbonate hardness) < 8, the water is also BAD, e.g. the water is not sufficiently pH buffered.
  • kH > 8, the water is HARD

Q1: What is CANNA CALMAG AGENT and why was it created?

A1: CANNA CALMAG AGENT is a water conditioner and pH stabilizer designed specifically for COCO substrates. It was created to address the challenges posed by varying water quality in Australia and New Zealand, and the use of soft water or Reverse Osmosis (R.O.) water in horticulture. It ensures the right balance of calcium and magnesium for plant nutrition.

Q2: How does CANNA CALMAG AGENT benefit plants grown on CANNA COCO substrates?

A2: The agent provides several benefits: it stabilizes the pH of water, reduces calcium and magnesium deficiencies, enhances nutrient uptake, promotes stronger plant growth, stimulates better quality flowers, and increases the Electrical Conductivity (EC) of water, ensuring plants receive all necessary nutrients.

Q3: What issue does CANNA CALMAG AGENT address when using soft water or R.O. water on COCO substrates?

A3: When using soft or R.O. water with COCO substrates, there's a complex interaction with divalent ions like calcium and magnesium. CANNA CALMAG AGENT controls this issue by providing a balanced addition of these ions, preventing overapplication of calcium and ensuring the availability of other essential nutrients like potassium.

Q4: How does CANNA CALMAG AGENT affect the hardness and EC of water?

A4: CANNA CALMAG AGENT makes water harder and increases its EC value. This is beneficial as it stabilizes the water, making it a suitable base for plants to absorb all needed nutrients effectively, especially when grown in COCO substrates.

Q5: Is CANNA CALMAG AGENT suitable for all types of plants?

A5: While CANNA CALMAG AGENT is specifically formulated for use with CANNA COCO substrates, it's primarily beneficial for plants that are sensitive to calcium and magnesium levels. It's best to consult specific plant requirements or an expert for other types of substrates or plants.