Help with Calcium Test Kits

Nick72

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21 Apr 2020
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I'm hoping to measure Calcium (Ca) in my freshwater planted aquarium.

Here in Malaysia I'm limited to :

Sera Calcium Test Kit

Or

API Calcium Test Kit

They both seem to be designed for marine water with 350-450 ppm Ca.

Will they work with Freshwater, and if so are they sensitive enough.

I'm dosing 45 ppm Ca per week. Thinking I have very low to no Ca in my tap.

I'll check both tap and aquarium when I get the test kit.
 

dw1305

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Hi all,
Will they work with Freshwater, and if so are they sensitive enough.
No and no. Marine aquarists need to continually add calcium because they keep organisms (hard corals, snails, coralline algae) that continually deplete the Ca++ and HCO3- ions. In freshwater it is bit different.
I'm dosing 45 ppm Ca per week. Thinking I have very low to no Ca in my tap. I'll check both tap and aquarium when I get the test kit.
That is more calcium than you need.

Personally I'd use a self-regulating low tech solution, which is to just add an aragonite calcium carbonate (CaCO3) source to your tank.

I like <"Oyster shell chick grit">, but coral sand, cuttle bone etc perform the same "buffering" role. It is a self regulating system because CaCO3 has very low solubility and will only go into solution as the pH, calcium and carbonate levels fall.

Do you have a <"conductivity meter?"> I use one, <"together with snail shell attrition">, to give me an idea of the base status of the tank water.

cheers Darrel
 
Last edited:

jaypeecee

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Bracknell
I'm hoping to measure Calcium (Ca) in my freshwater planted aquarium.
Hi @Nick72

If Mg and GH are measured, it ought to be possible to calculate Ca, assuming that GH of your tap water is mostly comprised of Ca and Mg ions. This is the approach that I take. I use the JBL freshwater Mg test kit and API GH test kit. Try also using this:

https://www.lenntech.com/ro/water-hardness.htm

JPC
 

Nick72

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Location
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Hi all, No and no. Marine aquarists need to continually add calcium because they keep organisms (hard corals, snails, coralline algae) that continually deplete the Ca++ and HCO3- ions. In freshwater it is bit different. That is more calcium than you need.

Personally I'd use a self-regulating low tech solution, which is to just add an aragonite calcium carbonate (CaCO3) source to your tank.

I like <"Oyster shell chick grit">, but coral sand, cuttle bone etc perform the same "buffering" role. It is a self regulating system because CaCO3 has very low solubility and will only go into solution as the pH, calcium and carbonate levels fall.

Do you have a <"conductivity meter?"> I use one, <"together with snail shell attrition">, to give me an idea of the base status of the tank water.

cheers Darrel

Hi Darrell,
While researching E.I. Dosing I read that 45ppm Ca and 15ppm Mg were the standard.

So that's what I've been dosing. Is this not correct?

I'm also dosing 21ppm Nitrate, 30ppm Potassium, 5ppm Phosphorus, 30ppm Sulfur.

CSM+B with 0.9ppm Fe from a combination of DTPA 7% and EDTA 13%

(each of above are per week)
 

Nick72

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Location
Kuala Lumpur, Malaysia
Hi @Nick72

If Mg and GH are measured, it ought to be possible to calculate Ca, assuming that GH of your tap water is mostly comprised of Ca and Mg ions. This is the approach that I take. I use the JBL freshwater Mg test kit and API GH test kit. Try also using this:

https://www.lenntech.com/ro/water-hardness.htm

JPC
Hi JPC,
Ca ppm = ((17.9 x dGH) - (4.1 x Mg ppm)) / 2.5

I've got a GH Test kit kicking around somewhere, but no Mg test kit.

It is water change day. I could do a big water change then add 15ppm Mg, then test GH.

I think it's safe to assume my tap water doesn't have much Mg as the GH is normally 1 maybe 2, before I push it up to around 8 or 9 with the above fertiliser regime.
 

jaypeecee

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Hi @Nick72

Would this be of any help?
No, it's not really the right piece of kit. In a conductivity meter, the electrodes are of a specific length, diameter and separation. That's why the units are microSiemens per centimetre, for example.

I think it's safe to assume my tap water doesn't have much Mg as the GH is normally 1 maybe 2, before I push it up to around 8 or 9 with the above fertiliser regime.
I don't know anything about Malaysian tap water. You're the best judge there. So, it looks like your GH will be a measure of calcium, doesn't it? Easy-peasy!

JPC
 

dw1305

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Hi all,m
While researching E.I. Dosing I read that 45ppm Ca and 15ppm Mg were the standard.
Yes and no, the ideal ratio of calcium (Ca) to magnesium (Mg) was given as 3:1, not every-one regards ratio <"as particularly important">, and I don't know where the 3:1 ratio came from. Many Americans have substantial amounts of magnesium in their <"tap water for geological reasons">, but in <"N. Europe we don't">.

The reason that calcium level is so high (45 ppm) because the majority of people have hard water, so that is water that starts out <"with a lot of calcium (Ca) in it">, it isn't because plants have a high calcium requirement, they don't.
In a conductivity meter, the electrodes are of a specific length, diameter and separation. That's why the units are microSiemens per centimetre, for example.
As @jaypeecee says same idea, but a different meter.

Have a look at <"TDS parameters...">. We can test really easily for calcium and magnesium <"in the lab. via AAS">, but for us it doesn't really help a lot because all the water samples we get in are "hard water" and they will be fully saturated with calcium and they won't have much magnesium in them.

cheers Darrel
 

sparkyweasel

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30 Jun 2011
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I think what's in that link is very simplified, in a 'fun with science' sort of way.
There are a couple of answers to the question here;
https://www.quora.com/How-can-I-measure-the-electrical-conductivity-of-water-using-a-multimeter
which go into more detail. One problem is that the electrodes are not really a suitable material. Conductivity meters are quite cheap and so much easier. Or a TDS meter, which works in the same way, but displays the result as total dissolved solids.
 
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