# Nutrafin Ca test kit



## Bryeman (Aug 24, 2009)

I have a Nutrafin Ca test kit, but when following directions, it only will show Ca levels down to 20ppm. Does anyone know if you can use this test kit, change the amount of water tested, and be able to alter the test parameters? For example, the test says to fill tube with 5ml of water and then perform test, but could I fill to 10ml and would this give me accuracy down to 10ppm per drop added? I know this works with some tests, but wondering if anyone smarter than me (most on here ) would know with regards to this specific test?


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## Philosophos (Mar 1, 2009)

I'm not sure myself, but it's easily tested. All you need to do is measure a liquid with the same level of calcium twice. If it's drop and shake, just use twice as much liquid and double the number of drops for 10ppm increments and it should give you a result indicating the same ppm's with a +/- 10ppm variation. If it changes color over time, it probably won't give you more accurate results.

I recommend calibrating test kits before using them, otherwise they aren't so accurate.

-Philosophos


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## Bryeman (Aug 24, 2009)

That makes sense. I'll try it and see what happens. It kind of looks like this should work. I was looking in the FAQ sticky and saw they mentioned Ca test kits and 5ml/10ml measurements.


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## Diana K (Dec 20, 2007)

To measure lower levels fill your test tube this way:
50% sample + 50% RO/DI then double the result. 
25% sample + 75% RO/DI then quadruple the result. 

Simply using more of whatever you are sampling will not do the trick.


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## Bryeman (Aug 24, 2009)

Diana K said:


> To measure lower levels fill your test tube this way:
> 50% sample + 50% RO/DI then double the result.
> 25% sample + 75% RO/DI then quadruple the result.
> 
> Simply using more of whatever you are sampling will not do the trick.


I don't see logically how what you describe will work? You are simply going to get the same result each time (the same as following the test directions)? I'm not a chemistry major, but it seems flawed. If I take 1/2 of something, then double it, I'll end up with the starting value, same if I start with 1/4 and quadruple it. Correct me if I'm wrong, but I'm having a hard time with this one.

I want to take twice the amount of tank water, and then perform the same test (since it's a "add drop until color changes" type of test like the Nutrafin GH/KH test kits). This should enable me to get readings down to 10ppm versus the normal 20ppm, or at least that was my question.


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## inwu (May 14, 2009)

Hi Bryeman,

I just order LaMotte "Total, Calcium & Magnesium hardness Test kit" from LaMotte. It's pricey (around $60 including shipping) but it can get your the resolution up to 4ppm. I recently encountered a potassium deficiency symptom but I am sure I have way enough potassium in the water. (LaMotte kit shows more than 50ppm) After researching on the web, I think the cause is the unbalance between K, Ca and Mg. BTW, I also have magnesium deficiency symptom!

Check this link:
http://go.aquaticplantcentral.com/?...w.finostrom.com.gr/images/fertilizers/map.htm

Seems like K, Ca and Mg will interfere each other if the relationship is not right. It also suggests that the K should be lower than Ca. I decide to try the following parameters and see how it goes.

APC Calculator recommend
K 15ppm 10-20ppm
Ca 22ppm 10-30ppm
Mg 5ppm 2-5ppm


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## Bryeman (Aug 24, 2009)

inwu said:


> Hi Bryeman,
> 
> I just order LaMotte "Total, Calcium & Magnesium hardness Test kit" from LaMotte. It's pricey (around $60 including shipping) but it can get your the resolution up to 4ppm. I recently encountered a potassium deficiency symptom but I am sure I have way enough potassium in the water. (LaMotte kit shows more than 50ppm) After researching on the web, I think the cause is the unbalance between K, Ca and Mg. BTW, I also have magnesium deficiency symptom!
> 
> ...


The problem I have is my tap water (well water, not city) spits out liquid Mg it seems. My GH is 4 or so out of the tap, and almost all of it is Mg. I have under 10ppm Ca and over 10ppm Mg out of the tap. I add Ca to my tank after each weekly water change, and don't add Mg. Growth is good to excellent again. I only had one issue that appeared to be Ca/Mg related possibly and that was cupped Bacopa leaves a while back. Everything currently seems to be doing well. Tough to make changes to my Mg concentration without looking at DI/RO water, and I'm not spending the money on that for my 125g. After my weekly water changes and additions, I'm roughly 15-20ppm Ca, 12ppm or so for MG, and I don't measure K, but I do add a little after water change and it's also added during P and N dosing.


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## inwu (May 14, 2009)

You should be happy with the good to excellent result. My tap water has more than 12dGH and I have no choice but use the RO water. Not to mention I still need to mess around with the chemicals in order to get the right condition. One thing ,though. With the rough resolution of Ca and GH test kit, the Mg result may not be what you expected. But if I were you, I probably will live with it. 

Good luck!


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## Bryeman (Aug 24, 2009)

You are correct about the testing results. With the lower end kits I have, who knows for absolute sure. I've calibrated most of my tests at one time or another, so I feel somewhat confident, but the Ca test I have is pretty weak when looking at the "per drop" range. I'll be the first to admit the actual ppm's could be off by a lot.

Thanks for your thoughts on this!


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