# Good source of Ca without adding S



## Bryeman (Aug 24, 2009)

My tap water (well water) has GH of about 4, and almost all of that appears to be Mg. From what I can tell according to a couple of test kits, Ca is less than 10ppm. Mg is over 10ppm. I currently add CaSO4, but would like a different source of Ca since I currently add K2SO4 and I'll be adding a lot of S if I continue with both! I would like to stay away from anything that alters KH as well. My KH is currently at 3 and I really don't want to mess with that for a couple of different reasons. Any ideas would be appreciated!


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## Zapins (Jul 28, 2004)

Well, there is the old standby CaCl that a lot of people use. 

Out of curiosity what are your test kit readings that lead you to those conclusions. Also, are your plants growing ok or are they stunting?


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## Bryeman (Aug 24, 2009)

Zapins said:


> Well, there is the old standby CaCl that a lot of people use.
> 
> Out of curiosity what are your test kit readings that lead you to those conclusions. Also, are your plants growing ok or are they stunting?


Test readings are constantly under or right at 10ppm for Ca (I've calibrated them best I can given the type of test and they seem fairly accurate). I can't pinpoint it, but it's 10 or under every time I test (tap water). That's with a GH of 4.  I don't have algae and haven't yet in this 125g since I started it back in September. I had some CO2 issues that I need to work out for the carpet plants, but that should be fixed now. I wouldn't call anything necessarily stunted, but I don't think I'm getting anywhere near the growth I should out of my L. repens and H. Corymbosa 'siamensis'. They are both growing, but pretty slow for the ferts and lighting they get. Like I said though, no algae and the plant color is good, so I don't want to get greedy ! I'm just worried about adding S for both my K and Ca dosing. I've been adding 3tsp of CaSO4 per week and 3/4tsp of K2SO4. More concerned than anything.


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## Zapins (Jul 28, 2004)

Hmm. This is somewhat strange since excess magnesium usually causes stunting and twisted new leaf growth. Ca:Mg ratio should be roughly 4:1. Sooo, based on what I remember about degrees and ppms. You should have ~61 ppm magnesium and only 10 ppm calcium, which is a 1:6 ratio. I'd like someone to verify this.


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## Diana K (Dec 20, 2007)

German degrees of hardness are 17.9 ppm. 

If GH is ONLY the measure of Ca and Mg, then the math is:

4 degrees * 17.9 = 71.6 ppm

71.6 ppm - 10 ppm (of Ca) = 61.6 ppm Mg

Calling that a ratio of 1 part Ca : 6 parts Mg is quite reasonable. It might be worse, if the test for Ca is not even showing as high as 10 ppm, then even more of the GH might be Mg. 

Calcium deficiency should show up on hard water plants such as Vals, they will fail to thrive, or die.


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## nfrank (Jan 29, 2005)

i believe that you got the calcium to magnesium ratios mixed up. Typically, natural soft waters have a Ca:Mg ratio of 3:1. Hard waters can be 10:1 (also with higher concentrations). Unless the Ca test is biased low, then Bryeman's water may have untypically high Mg. Zapins is more on the mark.

To get the Ca to Mg levels closer to the above proportions would mean raising the GH. which may not favor some plants. Before i made such a modficiation to my tank water, i would mix up a test solution of CaCL2 and see if i can "calibrate" the Ca test kit.

Regarding a good source of Ca, i have used both CaSO4 and CaCl2. The latter is much more soluble. I have used them in combination of MgSO4. Howver, I also use and favor Dolomitic coral in a filter or sump to get both in what i consider to be the desired ratio of 3:1. The trick is to use the correct amount of crushed coral so that the water does not get too hard. This could also be used by Bryeman which will shift the Ca:Mg ratio in the right direction, if the kit is in fact reading correctly.

BTW, I dont share the same concerns of others on the forum for high levels of sulfate(SO4). My tap water with KH and GH of approximately 1-2 degrees hardness has 25ppm SO4. The amount of SO4 to bring hardness up a few degrees is very small.... and will only raise my existing levels by a small percentage.
--Neil


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## Bryeman (Aug 24, 2009)

Diana K said:


> German degrees of hardness are 17.9 ppm.
> 
> If GH is ONLY the measure of Ca and Mg, then the math is:
> 
> ...


This is close, but not correct. 71.6ppm (GH) - 25 (which is the Ca hardness, for this I'm saying my ppm was 10)= 46.6 Mg hardness. You then take 46.6 and divide it by 4.1 and that will give you 11.37ppm of Mg. These formulas are posted on a sticky and on the back of the test kit I use.


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## Bryeman (Aug 24, 2009)

Zapins said:


> Hmm. This is somewhat strange since excess magnesium usually causes stunting and twisted new leaf growth. Ca:Mg ratio should be roughly 4:1. Sooo, based on what I remember about degrees and ppms. You should have ~61 ppm magnesium and only 10 ppm calcium, which is a 1:6 ratio. I'd like someone to verify this.


I had some posts about this a while back. When I first started this tank, I was adding some Epsom salt until I realized what my GH/Ca/Mg relationship was and obviously stopped immediately. My moneywort was shooting out new leaves that were unbelievably deformed (twisted, loops, very small leaves, etc.). There were several theories at that time. I know for a fact (given tap water plus what I was adding and measured when Ca test arrived that my Mg was 18+ppm at that time). I have well water, so the higher Mg out of the tap doesn't surprise me. Wish the Ca was higher though!

Currently, I'm getting my Ca to around 20ppm, with the Mg staying what it is out of the tap (10-14ppm likely). This gives me a GH of around 6 give or take.


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## Bryeman (Aug 24, 2009)

nfrank said:


> i believe that you got the calcium to magnesium ratios mixed up. Typically, natural soft waters have a Ca:Mg ratio of 3:1. Hard waters can be 10:1 (also with higher concentrations). Unless the Ca test is biased low, then Bryeman's water may have untypically high Mg. Zapins is more on the mark.
> 
> To get the Ca to Mg levels closer to the above proportions would mean raising the GH. which may not favor some plants. Before i made such a modficiation to my tank water, i would mix up a test solution of CaCL2 and see if i can "calibrate" the Ca test kit.
> 
> ...


Thanks for the thoughts on SO4. I think I will go with CaCL2 next time I order more. I like the more soluble part and this will cut the S in the tank whether it's doing anything or not.


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## Zapins (Jul 28, 2004)

Bryeman can you link to your previous posts about how to calculate the Mg levels from the Ca and GH levels? I remember there was some kind of trick to it but I don't remember what it was.


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## Bryeman (Aug 24, 2009)

Zapins said:


> Bryeman can you link to your previous posts about how to calculate the Mg levels from the Ca and GH levels? I remember there was some kind of trick to it but I don't remember what it was.


Here's the info.

Ca testing
((17.86 x dGH) - (4.1 x Mg ppm)) / 2.5 = Ca ppm

(ppm dGH - (4.1 x Mg ppm)) /2.5 = Ca ppm
-------------------------------------------------------
Mg testing
((17.86 x dGH) - (2.5 x Ca ppm)) / 4.1 = Mg ppm

(ppm dGH - (2.5 x Ca ppm)) /4.1 = Mg ppm

Hagen Nutrafin, Ca test in 10 ml
((20 x GH drops) - (25 x Ca drops)) /4.1 = Mg ppm

Hagen Nutrafin, Ca test in 5 ml
((20 x GH drops) - (50 x Ca drops)) /4.1 = Mg ppm
-------------------------------------------------------
GH testing
(2.5 x Ca ppm) + (4.1 x Mg ppm) = GH ppm

((2.5 x Ca ppm) + (4.1 x Mg ppm)) / 17.86 = dGH

All of this info is in the bottom "sticky" in the fertilizer thread section. "FAQ - Chemical mass, conversions............"


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## Edward (May 25, 2004)

There is not known S overdose, you can't harm anything with that. On the other hand Cl from CaCl2 causes problems at even low concentrations. So the only way to use CaCl2 correctly is with massive water changes. 
S from CaSO4 is actually an essential plant nutrient, you can not go wrong. More info &#8230;


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## Bryeman (Aug 24, 2009)

Interesting. You're the first to mention this. I'll wait for a few others to respond on that before jumping the gun. I've made some changes in the last week and things are starting to "click" in my tank. If this continues (ground cover spreading faster, etc.), I will stick with the CaSO4 for sure. I was more worried about adding so much S to my tank between the K and Ca I add. If what you say is completely accurate, I'd have to watch out for this because I have to add a fair amount of Ca to my tank weekly.

By the way, please don't take offense to "if what you say is completely accurate" statement. There's just a lot of people on here and it's amazing how different groups will say completely different things. I try to keep an open mind about all of this, and take things slow!


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## Edward (May 25, 2004)

As an example, I had a 90 gallon aquarium without water changes for over 3 years with CO2, RO, PPS Classic fertilization and CaSO4 as the only Ca source. Water so healthy Tetras were hatching eggs and maintaining multigenerational school of fish.


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## Bryeman (Aug 24, 2009)

Edward said:


> As an example, I had a 90 gallon aquarium without water changes for over 3 years with CO2, RO, PPS Classic fertilization and CaSO4 as the only Ca source. Water so healthy Tetras were hatching eggs and maintaining multigenerational school of fish.


Seems like pretty compelling evidence! 

I appreciate the experience. I have a lot of the CaSO4 left, but I add a lot per week, so I'll have to decide soon!


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## stevenlau (Jul 21, 2009)

Edward said:


> There is not known S overdose, you can't harm anything with that. On the other hand Cl from CaCl2 causes problems at even low concentrations. So the only way to use CaCl2 correctly is with massive water changes.
> S from CaSO4 is actually an essential plant nutrient, you can not go wrong. More info &#8230;


So sorry Edward to bring up the old thread but I'm dying to know what are the specific problems that Cl from CaCl2 would cause? Thank you very much.


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