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Epsom Salt (Magnesium sulphate)

SKU Epsom Salt 500g
Magnesium sulphate helps address magnesium deficiency in plants, and avoids sulphur deficiencies when used regularly. No added colours. No added fragrances. Harmless to fish when used correctly. . . . read more

Selected Size/Selection: 500 grams

500 grams
NOW $6.10 WAS $8.00 (AUD)

Out of Stock



Product Details

Magnesium is crucial for photosynthesis - the mechanism by which plants make energy from sunlight.  

The most noticeable sign of magnesium deficiency is yellowing of the leaf while its veins remain green (interveinal chlorosis).  It will first be noticeable in the older leaves, as the vital magnesium gets withrdrawn from them and sent to the newer leaves.  If left untreated, it will spread to the younger leaves, and can kill the plant in severe cases.

Your aquaponics system may have enough magnesium but, if there's too much potassium or calcium in comparison to the magensium level, you might still have problems.  Calcium and potassium compete with magnesium for uptake by the plant, so adding one of them can cause a deficiency in the others.  If your plants are showing signs of stress, it would be a great idea to get your water tested, if you can, so you can treat the proper problem.

This soluble magnesium sulphate, also known as Epsom Salt, has no added colours or fragrances, making it safe to use in your aquaponics system.  Simply add 1 tablespoon (20 mL) per 1000 L (~260 Gal) of water in the system, every week until the deficiency is resolved.  For severe deficiencies, mix 1 tbs in 4 L (~1 Gal) of water and spray directly onto the leaves.  Do not use this supplement if you are using hydrated lime to adjust the pH - the lime also contains magnesium, and you don't want to overdose your system.

When used regularly, magnesium sulphate also helps avoid sulphur deficiencies.

Each jar contains 500 g of magnesium sulphate (Epsom Salt), ready to dissolve in some water and add to your system.

If your plants have magnesium deficiency, this is thing to help!  Safe for your fish, great for your plants!



NOT FOR HUMAN CONSUMPTION.   Not stored or packed in food-safe conditions.

Additional Information


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