[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Adding Calcium (was APD V3 #924

Hello Bob,

The simplest way is to add CaCl2, obtainable in hardware stores for
de-icing. However, there is a danger that something might have been
added to it. I have seen CaCl2 *flakes* for sale in 5-gal buckets. That
is relatively pure. CaCl2 will lower your pH a little bit.

Dolomite -- CaMg(CO3)2 -- has both calcium and magnesium, so should be
your next choice. It is obtainable in garden stores for liming lawns
(but read the composition, whether it says "dolomite", "dolomitic",

Any strong acid, HCl (masonry), H2SO4 (pools) will do the job of
decomposing the carbonate. Here the problem will be NOT to acidify the
resulting solution too much with excess acid. 

I don't know how to figure out concentrations on something that is only
partially dissolved. What I would do, is make a kind of thin "soup" with
*excess* dolomite, so no excess acid is present. Let it settle overnight
and decant. 

Add a known volume of the supernatant to, say, 1 liter of water and
measure hardness. From that calculate how much "soup" you need for the

DON"T FORGET to change hardness sl-o-o-oowly, over days!

[I know, that you don't need that warning, but all of us sometimes get
overly impatient!  :-) ]



> I am trying to decide how best to add calcium without introducing carbonate
> hardness.  Myy NO3 tests around 10 ppm, so I could go with CaNO3.  Also CaCl
> is an option.  Is either of these available commercially, or do I need to make
> my own with dolomite and the appropriate acid?  If they are available, where
> at?  I could also use sulfuric acid from a swimming pool store.  My fish are
> SA cichlids and tetras, so I have been trying for a soft environment, I think
> maybe just not as soft as I have.  I'll pick up a hardness test tomorrow and
> detirmine GH and Calcium hardness before I start this.  Dosing recommendations
> for a 30 gallon with approximately 25 gallons net?
> Bob Dixon