# Calcium and Magnesium Deficiencies



## LindaC (Nov 7, 2005)

How would I know if I need to add calcium or magnesium to my tank? I have pretty soft water, with GH being at 40 ppms. My KH is low too, I buffer it by adding baking soda in my 29 gallon tank, I do not buffer it in my 10 gallon.
I read somewhere that if you have soft water, you should probably be adding calcium to your tank. 

Any thoughts?


----------



## Glouglou (Feb 21, 2006)

*Calcium, magnesium*

*Total Hardness (GH):]*
Calcium (approx.:55%) and Magnesium (approx.:25%) ions make the majority (about 80%) of cations (ions with a positive charge) in natural freshwaters. Na (sodium around 10% an other salts around 10%.

Dissolved salts such as calcium hydrogen-carbonate (Ca(HCO3)2) and calcium sulfate (CaSO4) are generally the main cause of hardness *(GH)* in water. Larger concentrations of calcium and magnesium salts means harder water; poor amounts of Ca and Mg salts means soft water.

*Bicarbonate (temporary) hardness of water (KH):]* 
Carbonate hardness is a measure of the concentration of hydrogen carbonate (HCO3-) ions in as long as there is at least one calcium or magnesium ion for each HCO3- ion in water. Note that per definition carbonate hardness KH can not be higher than total hardness GH.

With a GH of 40mg/l and I suppose a KH around 20, you probably a little low in calcium and magnesium.

I will ad some Mg (raise only GH) and some CaCO3 (Calcium carbonate, will raise both GH and KH) or some NaHCO3 ( baking soda will raise KH and less the GH) to have a KH around 30 (if you want low ph, if not, you can go higher) and a gh of 50, 60.


----------



## fabry (May 13, 2005)

Glouglou said:


> Note that per definition carbonate hardness KH can not be higher than total hardness GH.


Why?

Wrong definition?

Do not forget sodium or potassium.

If you pour into the water enough Sodium bicarbonate or Potassium bicarbonate you can raise kH well above gH.


----------



## Elkmor (Mar 30, 2005)

kH can be more than gH, in sample, if we put backing soda in RO water. My tap water has kH greater than gH.


----------



## MatPat (Mar 22, 2004)

Glouglou said:


> Note that per definition carbonate hardness KH can not be higher than total hardness GH.


I guess the definition has exceptions...while living in Maryland, I had well water with a GH of 4 dGH (~71ppm) and a KH of 7 dKH (125ppm).

The "definition" dose seem correct for my water here in Ohio but I now have a public system that is altered in many ways after leaving the ground.


----------



## Laith (Sep 4, 2004)

Glouglou said:


> *Total Hardness (GH):]*
> ...Note that per definition carbonate hardness KH can not be higher than total hardness GH....


I've seen this said before... I think it comes from the mistaken belief that KH is somehow part of GH. And this misunderstanding maybe comes from confusing definitions. I know that in Europe I sometimes read about how GH is "total hardness" and KH is only "temporary hardness". I think the thinking is that if calcium hydrogen-carbonate (Ca(HCO3)2) is one of the main components of GH, then the "carbonate" part of this compound is what causes the KH; therefore KH cannot be higher than GH since if you have more carbonate you will automatically increase the calcium as well.

I think this also has lead to the idea that subtracing KH from GH somehow gives you an indication of the amount of calcium...  .

I think Glouglou and I went through this on a previous thread some time ago. 

Of course, it could also be that I haven't understood anything about GH and KH and it's me that's been on the wrong track  .


----------



## MatPat (Mar 22, 2004)

To get back to your original question Linda, to know for sure if you need to add Ca or Mg to your tank you should have them both tested with a reputable kit. That will give you a good indication of where your levels are.

I would *guess* that you have plenty of Ca in the tank and *probabl*y enough Mg. If you were to be short of one or the other, MG would more than likely be the deficient nutrient.

You may also want to contact a few member of NEAPS (you are a member aren't you) and see what their water is like. Some may have the kits and be willing to test it for you or they may be able to point out a LFS with a good reputation for testing water. MA is a pretty small state so I would think the water wouldn't vary much from city to city. I could be wrong thought  Try contacting Dennis for more info on NEAPS or check out the Local Clubs Forums near the bottom of the main page.


----------



## BryceM (Nov 6, 2005)

Linda,

I recently moved from Worcester, MA and it sounds like we had similar water. I'd second the advice from MatPat. I was a member of NEAPS before leaving, and they're a great resource if you aren't already on-board with them.

I had a few issues with plants that seemed to improve once I started supplementing with Seachem Equilibrium. I'd add enough to get the GH up to 5 degrees or so.

As to the definition of GH and KH........
The nomenclature of these two terms is very unfortunate, since in reality they don't have much to do with one another. KH is a measure of a water's ability to buffer an acid or base. GH is a measure of a water's level of dissolved divalent cations (Ca & Mg are the most important).

In nature, most calcium and magnesium deposits occur as carbonate salts. Some Ca & Mg exists in other salts too. When rainwater passes over & through these deposits, over time some of it dissolves. It is usually true (sometimes not) that GH is higher than KH in naturally ocurring water supplies. Most of the buffering capacity of natural waters originates from these dissolved carbonates.

It is also true that one can artificially create water with any desired GH or KH quite independent of one another. Many municipalities do all sorts of crazy chemistry to modify the water before it gets to your house. What comes out of the tap can be completely unpredictable as municipalities change their practices from season to season and from year to year.


----------



## Edward (May 25, 2004)

Hi LindaC
You should be happy to have softer water. Ask your city water works for analysis. As long as there is any KH, Ca and Mg you are ok. Keep it simple.


----------



## HeyPK (Jan 23, 2004)

I have tap water with a KH of 11 and a GH of 0. It is nothing but a sodium bicarbonate solution with no calcium or magnesium. I don't use it, but collect rain water instead and get the GH level up to about 100 ppm by dissolving lime in it. The lime brings the pH up quite high, since it is mostly calcium and magnesium hydroxide, but I convert the hydroxides to carbonates and bring the pH down by adding CO2. 

I can't see any reason for adding sodium bicarbonate. It raises the pH and allows the water to hold more CO2, but adding calcium and magnesium carbonates does the same thing and it adds two essential nutrients. Plants don't need sodium. Fish need small amounts, but adding sodium bicarbonate just makes it harder for calcium or magnesium carbonates in snail shells, limestone, etc. to dissolve into the water.


----------



## Jimbo205 (Feb 2, 2006)

> adding sodium bicarbonate just makes it harder for calcium or magnesium carbonates in snail shells, limestone, etc. to dissolve into the water.


 I followed most if not all of that, but why would you ever want a snail's shell to dissolve in water?

Is this a way of saying that one of the benefits to snails is that their shells provide a latent or potential form of Calcium or Magnesium for when your tank needs it?

And, is one type of snail better than another? For example: is a Malasian Trumpet Snail better than a regular snail? I ask because when I tried Diana Walstad's idea of fish food providing supplements for my plants; I ended up with a snail EXPLOSION. That has died down now. But I am still in the process of learning some of the benefits of snails. (Like dead snail shells being good for my planted aquarium.)


----------



## HeyPK (Jan 23, 2004)

> I followed most if not all of that, but why would you ever want a snail's shell to dissolve in water?
> 
> Is this a way of saying that one of the benefits to snails is that their shells provide a latent or potential form of Calcium or Magnesium for when your tank needs it?


Snails take calcium and probably also magnesium out of the water when they make their shells, and when they die, the shells lie around for a long time slowly dissolving and returning the Ca and Mg. If you try to get your Ca & Mg up by adding ground limestone, it is the same process as snail shells dissolving. It is slow. Having sodium bicarbonate in the water raises the pH and slows down the process even more.


----------

