# Options for adding calcium to water.



## Sharkfood

Another thought:

Could I use bone meal? I know that contains alot of phosphorus also though.


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## Jadelin

You could buy something like this:

http://www.greenleafaquariums.com/aquarium-fertilizers-supplements/calcium-sulfate.html

(CaSO4 Calcium Sulfate)

Which is intended for aquarium plant use and won't add anything you're not looking for. (And it's only $2.50/pound.)


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## houstonhobby

Aquariumferts.com has calcium carbonate for 3.00 per pound. I use it mostly to raise my Kh, but it works for Gh too. Not very soluable but given time (and a little acid from the fish and the CO2) and it will get the job done.

Then there is also Barr's GH booster, from the same source. Adds both magnesium and calcium. Also not very soluable.


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## Imaginary1226

cuttlebone or whole oyster shells.


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## Sharkfood

Looks like aquariumfertilizers.com is my best bet.


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## DavidZ

what about CC(crushed Coral) or whole coral?


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## leaf

Crushed eggshell. Yummy.


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## TheVisionary78

I buy the little white calcium turtles ment for aquatic reptile tanks. They dissolve over time and do a great job of never over increasing the hardness. I use this method for my invert tanks.


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## zephyrae13

*Increasing hardness*

I've found that a piece of limestone works well for this purpose, and it also increases the buffering capacity of your tank. Although, I'm sure weathered bones would work too. ; )


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## Sharkfood

I thought about limestone, but I just don't like the idea of not being able to control the level in the water. I may be incorrectly identifying nutrient deficiency also. My water from the tap shows a Kh of 4 and from the tank before water changes I get around 2. I know limestone is prolific in our area. I'm getting stunted nodes on some rotala, and it looks like calcium deficiency to me. I'm not sure what else it could be. I was under the impression any kH over 1 was enough. I have plenty of CO2 in the tank. My nitrates do bottom out if I miss a day dosing, which can happen when I get called away overnight for my job, but I thought that affected plants primarily by turning old growth yellow.


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## KevinC

Two of the Ca supplements you mention are not water soluble - they are just like limestone (oyster and calcium carbonate) so not very controlled. Calcium citrate might be more organic matter (citrate) than you would want (promote bacterial growth and green water?). Soluble calcium would include calcium sulfate, calcium nitrate (added N might be a benefit) and calcium chloride.


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## dannyfish

Jadelin said:


> You could buy something like this:
> 
> http://www.greenleafaquariums.com/aquarium-fertilizers-supplements/calcium-sulfate.html
> 
> (CaSO4 Calcium Sulfate)
> 
> Which is intended for aquarium plant use and won't add anything you're not looking for. (And it's only $2.50/pound.)


Hi 
Will this CaSO4 will make the water cloudy?
I dosing calcium carbonate and this caused my tank water to become very cloudy ...OPS


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## Darkblade48

KevinC said:


> Soluble calcium would include calcium sulfate, calcium nitrate (added N might be a benefit) and calcium chloride.





dannyfish said:


> Hi
> Will this CaSO4 will make the water cloudy?
> I dosing calcium carbonate and this caused my tank water to become very cloudy ...OPS


Calcium sulfate is not soluble in water, to any appreciable amount.

Calcium nitrate is more soluble, as I mentioned in your other thread. Calcium chloride would be undesirable due to the addition of the chloride anion.

Why are you adding calcium carbonate, by the way?


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## KevinC

Darkblade48 said:


> Calcium sulfate is not soluble in water, to any appreciable amount.


CaSO4 solubility isn't great, but it is about 0.2g per 100ml - or about 7.5g per gallon. That's way more than needed for calcium supplementation (raising gH). Even the dihydrate form is 23% Ca, so to raise GH by 5 degrees (90ppm Ca) requires only 0.04 g per 100ml (1.5g per gallon). If the water is high in sulfate already then there is the common ion effect lowering solubility, but that's the only problem.


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## Darkblade48

Good point! Thanks for double checking my math; I was in a rush


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