How to Buffer a 5kg Compressed Washed Coco Coir Block

Even if your coco coir block is pre-washed to remove excess salts, it still needs to be buffered. Coco coir naturally holds onto potassium and sodium. If you don’t buffer it, the coir will absorb the calcium and magnesium you feed your plants, leading to severe nutrient deficiencies.

Buffering fixes this by pre-loading the coir with calcium and magnesium.

What You Need:

• 1x 5kg compressed washed coco coir block

• A large container or wheelbarrow (capable of holding at least 70 litres)

• 25 to 30 litres of clean water

• A Calcium-Magnesium (Cal-Mag) hydroponic supplement

Step-by-Step Instructions:

1. Prepare the Solution: Fill your container with 25 to 30 litres of water. Add your Cal-Mag supplement to the water. Check the label on your specific Cal-Mag product for buffering ratios—you will typically use double the normal feeding dose. Stir the solution well.

2. Hydrate the Block: Place the 5kg compressed coco coir block into the Cal-Mag solution. As it absorbs the liquid, it will begin to expand and break apart. You can speed up the process by gently breaking the softening chunks apart with a spade or your hands.

3. Soak Once the block is fully expanded and broken down, leave the mixture to soak for 8 to 24 hours. This soaking period is critical; it gives the cation exchange (a reversible chemical process where positively charged ions (cations) in an aqueous solution are exchanged for different cations bound to the surface of an insoluble solid material, such as clay, organic matter, or resin) sites in the coir enough time to release any remaining sodium and lock in the calcium and magnesium.

4. Drain After the soaking period is complete, drain any excess liquid from the coir. Because your block was already washed prior to this process, you do not need to rinse it again with plain water. But if not washed, please rinse the block a few times.

Your coco coir is now fully buffered, hydrated, and ready to be mixed with soil, perlite, or compost for your plant boxes!

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