# Calcium Nitrate/epsom salts - How much to add?



## tj.shulman (Mar 8, 2011)

hi guys,
I have a calcium deficiency in my hydro grow. I am using coco coir and my plants are in really bad shape.

I have bought 500g of Calcium nitrate and 500g of magnesium sulphate to make my own cal-mag diy additive. I found a recipe by 'fatman' but I am confused by the amounts needed and concentrations.

Could someone give me a quick idea of how to make a concentrated solution with these 2 chemicals, and how much of that solution to add to my rez.(60L)

Ballpark figures will be fine, I just need to save my plants quickly. I would get some cal-mag, but its not available here.

Thanks guys. (free karma to anyone kind enough to help!)


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## Atomizer (Mar 8, 2011)

You can`t mix calcium nitrate and magnesium sulphate together in a concentrated form as it`ll precipitate as calcium sulphate (gypsum). 
Commercial cal-mag formulas tend to use magnesium nitrate for the mag component which is compatable with calcium nitrate.

If you have a reasonably good set of scales this will get you close to botanicare`s cal-mag plus dosage of 10ml / 4L (excluding the sulphur content that comes from the magnesium sulphate) 
add each salt seperately and mix well.

calcium nitrate: 1.87g per us gal
Epsom: 0.3g per us gal
chelated iron: 0.076g per us gal


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## shadowdarker (Mar 8, 2011)

hey just been asking this question in newbie central. i have bought epsom salts to add to my res just as a supplement. what benefits does it give the plants? and also whats a us gallon in litres?? got a 10 litre res rougly 0.6g to my res going by your calculations? im british different weights and measures to you.


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## Atomizer (Mar 8, 2011)

You don`t need to add epsom (magnesium sulphate hyptahydrate) unless you see a deficiency but as a guide 1g/Litre will give you 98.6ppm of magnesium and 130ppm of sulphur.
Cal-Mag Plus at the recommended dose (10ml / 4L) adds 31ppm Mg, 84ppm Calcium, 2.6ppm Iron and 53ppm Nitrogen. One us gal = 3.785L,


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## shadowdarker (Mar 8, 2011)

thank you just what i needed to know


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## tj.shulman (Mar 8, 2011)

Thanks for the help Atomizer, I'll just make a separate calcium nitrate concentrate without the epsom salts.*

So to be clear (having a slow day)
1.87g Calcium Nitrate per gallon of rez water?
*


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## Atomizer (Mar 8, 2011)

Aye, 1.87g per us gal, that will give you 58ppm nitrogen and 84ppm calcium.


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## tj.shulman (Mar 9, 2011)

Just one more question,

Is it possible to use Calcium hydroxide in hydro? 
I have read that it is somewhat soluble in H2O, but the PH is very high.

Would it be ok if neutralised? If so, How much to add to the Rez?

Thanks!


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## Atomizer (Mar 9, 2011)

I would stick with calcium nitrate.Apart from the ph issues, calcium hydroxide is ~700x less soluable than calcium nitrate.


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## Gardna (Jan 30, 2013)

Trying the calcium and magnesium nitrate together, but is the chelated iron essential aswell? What purpose does it serve? Can I just mix the cal/mag nitrate without?


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