# It is safe to use calcium nitrate to fertilize my tank?



## sergio sinay (Nov 12, 2011)

As the title say i been using that for 2 days now, but im not completely sure if thats safe to use. The fish seems to be fine and my tank is a 30gal medium planted. I been ading 1/4 teaspoon of that and today was the 2nd dosage.


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## plantbrain (Dec 15, 2003)

Ca(NO3)2 is fine for use in softer low GH water. Most use a mix of Mg(NO3)2 and Ca(NO3)2 to add a good mix of Mg and Ca, or some use GH booster.

Once they are in the water, these ions disassociate so their dry salt sources do not matter. Ca++ is still Ca++ regardless.


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## sergio sinay (Nov 12, 2011)

Oh thx for the quick anwser i was worried about using that!


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## Diana (Jan 14, 2010)

Plants use calcium and nitrate. If the water already has plenty of calcium you might not want to add more, but as Tom says, in soft water (low GH) you may very well need both calcium and magnesium.


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## sergio sinay (Nov 12, 2011)

Thx for the reply! Now what would be the effects on the plants if im adding too much calcium?


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## plantbrain (Dec 15, 2003)

sergio sinay said:


> Thx for the reply! Now what would be the effects on the plants if im adding too much calcium?


I've never seen any toxic upper limits and no one has reported any to the best of my knowledge and that anyone else could verify independently.

All nutrients have upper limits, but they might be so high they are impractical to concern ourselves with, Ca is one such and perhaps SO4 etc.


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## sergio sinay (Nov 12, 2011)

Thx for the quick reply again!


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## jonnythe (Aug 6, 2007)

Sergio, are you dosing calcium nitrate only because you can't get potassium nitrate? 

If so, then it's quite simple (and fun) to turn the Ca(NO3)2 into KNO3 by reacting it with potassium sulfate. This is how I make my reasonably pure KNO3 since I have a virtually unlimited supply of calcium nitrate from my vineyard assistant brother, and K2SO4 is relatively cheap and easy to find.


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