http://www.americanagritech.com/supplements/cal-mag
if you are having a hard time finding it for plants, you may be able to use a human health food supplement such as this
http://www.affordablesupplements.com/cal_mag_fizz.asp
look at the label though. everything looks ok except for the "Mineral Blend" at the top, and the "citric acid fructose" in the ingredients. If I was desperate, broke, or just couldnt find it anywhere I would use something like this in a very low dose, like 2.5 ml to a gallon of water. hope this helps ya
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Mineral Blend: - 10 mg [/FONT]
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Total Carbs (g) - 1.5 [/FONT]
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Sugars (g) - 1.5 [/FONT]
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Calcium (mg) - 500 [/FONT]
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Vitamin D (IU) - 200 [/FONT]
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Magnesium (mg) - 200 [/FONT]
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Vitamin B1 (mcg) - 750 [/FONT]
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Vitamin B2 (mcg) - 850 [/FONT]
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Vitamin B3 (mg) - 10 [/FONT]
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Vitamin B6 (mg) - 1 [/FONT]
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Vitamin B 12 (mcg) - 3 [/FONT]
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Ingredients: citric acid fructose, stevia rebeudenia, natural flavor, natural color. [/FONT]