MichaelJ
Member
Hello,
This has being brought up from time to time in remineralizing related threads, and I wanted to hear what the chemistry experts and people with experience and knowledge of the pros and cons have to say on the topic of Calcium Chloride (CaCl2) vs. Calcium Sulphate (CaSO4). My own motivation for using CaSO4 is the lower TDS footprint from CaSO4 compared to CaCl2. I have used both and haven't experienced issues with either (although I only used CaCl2 for a few months last year, but CaSO4 for years - first with Equilibrium and later from individual salts).
When targeting 25 ppm of Ca (a very common situation):
With CaSo4 you get 20 ppm of S (Sulphur) totaling 45 ppm. Solubility ~0.26 g/100ml
With CaCl2 you get 44 ppm of Cl (Chloride) totaling 69 ppm. Solubility ~85 g/100ml
For a practical translation into TDS I ran the tests in 3 liters of RODI water targeting ~25ppm and measured the TDS with my Hanna DIST1:
0.32g of CaSO4 = TDS ~62 ppm.
0.27g of CaCl2 = TDS ~86 ppm.
Both Sulphur and Chloride are essential nutrients for plants. Plants absorb Sulphor as Sulphate (SO4), and is considered a Macro nutrients, but as a weekly target we probably don't need more than perhaps a few ppms of S in the form of SO4 - anyone knows? much, much less so for Chloride given that is generally characterized as trace element.
One thing that often comes up as an advantage for CaCl2 is the solubility vs. CaSO4. CaCl2 is orders of magnitude more soluble than CaSO4, but in my experience the solubility one vs. the other seems to be a non-issue IF you target moderate to low GH and add the dosing to the WC water or tank right away. For instance, at 0.26g/100ml you will have to add 26 grams into 10 liter to get to the limit - thats 605 ppm of Calcium! If you target the aforementioned 25ppm of Ca you will only add ~1g or ~26 times below to solubility limit, to a 10 liter volume. However, if you pre-mix CaSO4 in a smaller dosing bottle for several applications (high concentration) you will likely have trouble dissolving the CaSO4.
I have noticed that no commercial freshwater GH remineralizers (that I am aware of) are using Calcium Chloride. This is not a raw material price consideration as far as I can tell, as Calcium Chloride is generally somewhat cheaper than Calcium Sulphate.
Now, one thing I read recently with the issue of sulfates is that under severe anaerobic conditions at the substrate level the sulphate may convert into H2S (Hydrogen sulfide - a very toxic gas even at <1 ppm) - when or at what SO4 levels that might happen I do not know. I saw a note about this from D. Walstad in at another forum as well, and believe our member @X3NiTH might have experienced this (would be great to hear more about this @X3NiTH).
I don't really consider toxicity at the water column level one vs the other as we are usually not targeting levels high enough for that to be a problem for our livestock (both Sulphate and Chloride are bad in very high concentrations anyway...). But Chloride might be an issue nevertheless... At least around here in Minnesota Chloride run-offs (mostly from road salt) is a problem for natural waterways: Chloride 101.
So the question is, would our plants be more or less "happy" with CaSO4 vs. CaCl2 with respect to uptake, interaction with other chemicals etc? That would be interesting to know.
Cheers,
Michael
This has being brought up from time to time in remineralizing related threads, and I wanted to hear what the chemistry experts and people with experience and knowledge of the pros and cons have to say on the topic of Calcium Chloride (CaCl2) vs. Calcium Sulphate (CaSO4). My own motivation for using CaSO4 is the lower TDS footprint from CaSO4 compared to CaCl2. I have used both and haven't experienced issues with either (although I only used CaCl2 for a few months last year, but CaSO4 for years - first with Equilibrium and later from individual salts).
When targeting 25 ppm of Ca (a very common situation):
With CaSo4 you get 20 ppm of S (Sulphur) totaling 45 ppm. Solubility ~0.26 g/100ml
With CaCl2 you get 44 ppm of Cl (Chloride) totaling 69 ppm. Solubility ~85 g/100ml
For a practical translation into TDS I ran the tests in 3 liters of RODI water targeting ~25ppm and measured the TDS with my Hanna DIST1:
0.32g of CaSO4 = TDS ~62 ppm.
0.27g of CaCl2 = TDS ~86 ppm.
Both Sulphur and Chloride are essential nutrients for plants. Plants absorb Sulphor as Sulphate (SO4), and is considered a Macro nutrients, but as a weekly target we probably don't need more than perhaps a few ppms of S in the form of SO4 - anyone knows? much, much less so for Chloride given that is generally characterized as trace element.
One thing that often comes up as an advantage for CaCl2 is the solubility vs. CaSO4. CaCl2 is orders of magnitude more soluble than CaSO4, but in my experience the solubility one vs. the other seems to be a non-issue IF you target moderate to low GH and add the dosing to the WC water or tank right away. For instance, at 0.26g/100ml you will have to add 26 grams into 10 liter to get to the limit - thats 605 ppm of Calcium! If you target the aforementioned 25ppm of Ca you will only add ~1g or ~26 times below to solubility limit, to a 10 liter volume. However, if you pre-mix CaSO4 in a smaller dosing bottle for several applications (high concentration) you will likely have trouble dissolving the CaSO4.
I have noticed that no commercial freshwater GH remineralizers (that I am aware of) are using Calcium Chloride. This is not a raw material price consideration as far as I can tell, as Calcium Chloride is generally somewhat cheaper than Calcium Sulphate.
Now, one thing I read recently with the issue of sulfates is that under severe anaerobic conditions at the substrate level the sulphate may convert into H2S (Hydrogen sulfide - a very toxic gas even at <1 ppm) - when or at what SO4 levels that might happen I do not know. I saw a note about this from D. Walstad in at another forum as well, and believe our member @X3NiTH might have experienced this (would be great to hear more about this @X3NiTH).
I don't really consider toxicity at the water column level one vs the other as we are usually not targeting levels high enough for that to be a problem for our livestock (both Sulphate and Chloride are bad in very high concentrations anyway...). But Chloride might be an issue nevertheless... At least around here in Minnesota Chloride run-offs (mostly from road salt) is a problem for natural waterways: Chloride 101.
So the question is, would our plants be more or less "happy" with CaSO4 vs. CaCl2 with respect to uptake, interaction with other chemicals etc? That would be interesting to know.
Cheers,
Michael
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