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Discussion Starter · #1 ·
Hi,

A few people have recommended to me that I should use Calcium Chloride (CaCl2) instead of Calcium Sulfate (CaSO2.2H20) because CaCl2 is much more soluble.
Link Below:


Some Calcium salts are much more soluble than others. The least soluble common salts are Calcium Carbonate, which is basically chalk, and Calcium Sulfate, which is basically plaster of Paris.

Look at the solubility numbers in neutral pH water at 20 degrees C.:
Calcium Carbonate: 0.15 grams can be dissolved in 100ml
Calcium Sulfate: 0.25 grams can be dissolved in 100ml
Calcium Chloride: 74.5 grams can be dissolved in 100ml
Calcium Nitrate 121.2 grams can be dissolved in 100ml

It's no contest. Calcium Nitrate is almost 600 times more soluble that Calcium Sulfate.

Then ofcourse, others say I should stick with CaSO4 because although CaSO4 dissolves slowly, CaCl2 precipitates after you add it to your aquarium, then you have to wait for the CaCl2 precipitate to dissolve as well. So it does not matter in the end, use either one.

Link below:


Also note, I know Tom Barr uses CaSO4 mixed in his GH booster.

Can I get some advice on which one to use and why?

Thanks
 

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I use calcium chloride because I already had it at my house and I was concerned about too much sulphate encouraging the creation of hydrogen sulfide in my soil layer. I am not sure that's a legitimate fear now, but that was my thinking at the time. Anyway, if I mix calcium chloride and epsom salt together at too high of a concentration it does precipitate, but seems to dissolve back in the tank pretty quickly, within an hour. The precipitate doesn't form if I add them separately to the tank, so I just do that.

I am interested to see if anyone else thinks it matters. I feel pretty ambivalent about my choice overall.
 

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Discussion Starter · #3 ·
I use calcium chloride because I already had it at my house and I was concerned about too much sulphate encouraging the creation of hydrogen sulfide in my soil layer. I am not sure that's a legitimate fear now, but that was my thinking at the time. Anyway, if I mix calcium chloride and epsom salt together at too high of a concentration it does precipitate, but seems to dissolve back in the tank pretty quickly, within an hour. The precipitate doesn't form if I add them separately to the tank, so I just do that.

I am interested to see if anyone else thinks it matters. I feel pretty ambivalent about my choice overall.
So you're saying MgSO4 by itself is enough sulfur?
If so, then that's +1 for the CaCl2.
 

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Usually there's a significant amount of sulphates already in the water supply, so additional supplementation isn't needed. This is also true for chloride, so if you'll notice that people who mix their own ferts usually don't list them.
 

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Discussion Starter · #5 ·
Usually there's a significant amount of sulphates already in the water supply, so additional supplementation isn't needed. This is also true for chloride, so if you'll notice that people who mix their own ferts usually don't list them.
Do you store your Calcium Chloride in dry form? or do you make a solution immediately after you obtain it? I ask because I've read that the dry form absorbs moisture after a while and gets ruined, thus the need to make solution.
 

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I do store it in dry form. It's in air tight packaging with one of those do-not-eat desiccant packet and the whole package itself is in a plastic container in case it leaks. I have witnessed a pre-measured amount turn start to turn briny sitting out on my counter for a couple of hours, but I didn't see any reason I couldn't still use it. It is likely that the little pellets in the storage container have absorbed some water over time and it's throwing off my measurements some, but in this application I'm not worried about the inaccuracy. I do monitor both my GH and TDS and haven't found them to be much different than expected. This is good enough for me, I think.
 

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Do you store your Calcium Chloride in dry form? or do you make a solution immediately after you obtain it? I ask because I've read that the dry form absorbs moisture after a while and gets ruined, thus the need to make solution.
1029496

Thanks for mentioning Calcium Chloride is hydroscopic. I wasn't aware of that. I just got this big bag of silica gel packets yesterday. I've stored hydroscopic compounds for years without silica gel though. I always put a smaller amount in a smaller container. Then I don't open the big container until I need it again. I also have a mortar and pestal for when compounds clump.
1029497

I am more a proponent of CaCl2 than CaSO4 but I use mostly the latter. I use 1/4 the amount of CaCl2 to 3/4 the amount of CaSO4. The concensus seems to favor using CaSO4. I tried to get my CaCl2 from Green Leaf Aquariums but they don't sell it. It's used in salt water setups of course. Dr. Barr says you can have as much as 200 ppm Sulfate and not worry about it. Then the argument goes that Chloride isn't necessary.

As far as solubility, I vigorously shake my remineralizing compounds in half a gallon of water before adding them to a bucket with a powerhead. I let the powerhead mix things up for three to ten minutes. But what I have found, is that it is the CaCl2 pellets that do not dissolve after shaking in water. The CaSO4, now I realize thanks to your post, also does not dissolve and goes into the bucket clouding the water. But at least it's not solid like the Calcium Chloride. The powerhead gets removed after mixing a while and there is no precipitate visible in the bottom of the five gallon storage bottles.

And then there's this unrelated gem about Calcium Chloride that I just have to share:

 

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Speed of dissolution is one thing but, if you know the solubility limit (most are identified in calculators such as RotalaButterfly and Zorfox’), they will all dissolve in acidic water (pH < 7) within a day. In alkaline water (pH>7), some may not dissolve as readily. These limits are the numbers that you listed, although I didn't verify your actual numbers.

If the focus is upon Ca, and not the other ions, then you would select the easiest one that dissolves, but also being concerned about the other ion. For example, I generally don’t want more than about 7ppm of Chloride. If you keep dosing CaCl, how much Chloride will accumulate over time (see RoralaButterfly nutrient accumulation calculator)? If it is too much, you may want to use a combination of CaCl and CaSO4. Sulfates are generally not known to cause problems in excess, but I do have a nagging suspicion that they do à la Mulder’s chart. Ca(NO3) gives you a lot of nitrate for the Ca. It may be too much NO3 but, again, maybe you can use it in combination with other Ca salts. For pure Ca only, you can dose Ca gluconate.

For my specific purposes, as an example, I dose a small quantity of CaCl up to the Cl limit of about 3ppm (knowing that the Cl will accumulate to 7ppm or so, over time). The bulk of the Ca is then delivered by CaCO3 because I am constantly trying to add KH to maintain pH in the 5.8-6.2 region (if needed, I can get a full dKH with CaCO3 within a day). If I don't need much carbonate, I may get it from KHCO3 and dose either Ca gluc or, if I sense that more SO4 is needed (maybe my Mg hasn't been added with enough SO4 recently), I'll use CaSO4.

The point is that you have a great deal of flexibility to mix and match all of the salts we have at our disposal, depending upon how you want to keep your nutrients balanced. It kinda makes it more interesting.
 

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...For example, I generally don’t want more than about 7ppm of Chloride. If you keep dosing CaCl, how much Chloride will accumulate over time (see RoralaButterfly nutrient accumulation calculator)? If it is too much, you may want to use a combination of CaCl and CaSO4....
This was my exact thought process as well.

I use a combination of CaCl and CaSO4.

Anecdotally, in the past I only used CaCl, and overtime, my plants would inexplicably start to struggle horribly. Even with everything remaining the same. I eventually contributed it to the accumulation of Cl because I couldn't figure out anything else (I tested and monitored everything else that I could). I wish I would have tested the water some way for Cl concentration. Since I switched to the combo, I have not seen my plants go through that same problematic phase.

However, saying that, I have seen tanks that appear to by thriving, and when I inquired about their ferts they told me that they were only using CaCl for their GH. So I still always wonder.

I also keep my ferts in a closable container with desiccant packets. The exact same ones pictured above.
 

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Discussion Starter · #10 ·
I do store it in dry form. It's in air tight packaging with one of those do-not-eat desiccant packet and the whole package itself is in a plastic container in case it leaks. I have witnessed a pre-measured amount turn start to turn briny sitting out on my counter for a couple of hours, but I didn't see any reason I couldn't still use it. It is likely that the little pellets in the storage container have absorbed some water over time and it's throwing off my measurements some, but in this application I'm not worried about the inaccuracy. I do monitor both my GH and TDS and haven't found them to be much different than expected. This is good enough for me, I think.
When the Cacl2 absorbs moisture, do we get harmful bacterial concerns? I know its an inorganic compound, but that might change after water absorption. If there are no bacterial concerns, I plan on bashing the clumps with a mortar and pestle prior to dosing.

View attachment 1029496
Thanks for mentioning Calcium Chloride is hydroscopic. I wasn't aware of that. I just got this big bag of silica gel packets yesterday. I've stored hydroscopic compounds for years without silica gel though. I always put a smaller amount in a smaller container. Then I don't open the big container until I need it again. I also have a mortar and pestal for when compounds clump.
View attachment 1029497
I am more a proponent of CaCl2 than CaSO4 but I use mostly the latter. I use 1/4 the amount of CaCl2 to 3/4 the amount of CaSO4. The concensus seems to favor using CaSO4. I tried to get my CaCl2 from Green Leaf Aquariums but they don't sell it. It's used in salt water setups of course. Dr. Barr says you can have as much as 200 ppm Sulfate and not worry about it. Then the argument goes that Chloride isn't necessary.

As far as solubility, I vigorously shake my remineralizing compounds in half a gallon of water before adding them to a bucket with a powerhead. I let the powerhead mix things up for three to ten minutes. But what I have found, is that it is the CaCl2 pellets that do not dissolve after shaking in water. The CaSO4, now I realize thanks to your post, also does not dissolve and goes into the bucket clouding the water. But at least it's not solid like the Calcium Chloride. The powerhead gets removed after mixing a while and there is no precipitate visible in the bottom of the five gallon storage bottles.

And then there's this unrelated gem about Calcium Chloride that I just have to share:

Have you noticed any harmful bacterial concerns after applying the amount that clumped? I ask because organic powders (like pre-workout supplements and aminoacids) will harbor harmful bacteria after moisture absorption.
 

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Have you noticed any harmful bacterial concerns after applying the amount that clumped? I ask because organic powders (like pre-workout supplements and aminoacids) will harbor harmful bacteria after moisture absorption.
The Calcium Chloride has not clumped. My Potassium Nitrate did clump but stayed clean. The only other one that clumped badly was Potassium Bicarbonate. It also did not get contaminated. But I believe you. There are all sorts of potential contaminations lurking in this hobby. You do have to be careful. Moisture is a big culprit.
 

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Sulfates are generally not known to cause problems in excess, but I do have a nagging suspicion that they do à la Mulder’s chart.
You know, I haven't seen any good research that supports Mulder's chart. There's lots of research about nutrient uptake interactions, but outside N, P, and K uptake acting synergistically the direction of the interactions varied between studies. If you have any literature about it I'd love to give it a read. These interactions definitely seem to exist, but they may vary by species, environmental conditions, etc.

When the Cacl2 absorbs moisture, do we get harmful bacterial concerns? I know its an inorganic compound, but that might change after water absorption. If there are no bacterial concerns, I plan on bashing the clumps with a mortar and pestle prior to dosing.
I haven't seen any evidence of anything growing and it's not something I'm concerned about. My calcium chloride comes as prills and I don't bother to grind them up at all. They dissolve readily.
 

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You know, I haven't seen any good research that supports Mulder's chart. There's lots of research about nutrient uptake interactions, but outside N, P, and K uptake acting synergistically the direction of the interactions varied between studies. If you have any literature about it I'd love to give it a read. These interactions definitely seem to exist, but they may vary by species, environmental conditions, etc.
First, there are virtually no studies, for most aspects of nutrients, which have been done in our hobby. So, we are left with studies performed on terrestrial plants, plants in hydroponics and, occasionally, ecological studies regarding plant involvement in lakes, streams and oceans. IMO, hydroponics is about as close as we can get to our hobby, although some ecological studies can apply. There is, however, difficulty with hydroponics, as well. That industry focuses upon things like soilless uptake, flowering, vegetable production, etc. Nothing is perfectly applied to our hobby.

The nutrient interaction links that I’ve found interesting enough to save, are: here and here

I’ve seen much more, but didn’t save anything other than quotes, re-phrasing of concepts and registering info in my brain. However, there are many studies out there, including Mulder’s original work. Hopefully, others can add their own links to studies/info.

There is also the area of ionic balancing, which is loosely connected to the larger nutrient interaction game.
 

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There is also the area of ionic balancing, which is loosely connected to the larger nutrient interaction game.
Is ionic balancing where we get all our dosing ratios from? The 3 to 1 Calcium to Magnesium and the 10 to 1 Nitrate to Phosphate and others?
 

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@Deanna Thanks for the links. I definitely agree that it is unclear if/how a lot of existing plant research would hold up in the hobby. Actually, this is one reason that the hobby is interesting to me is that is takes the typical plant growing situation and turns it on its head. A world where plants are carbon limited and water status is a given instead of the other way around ? So radical! I wish I had gotten deeper into plant nutrition somewhere in undergrad or grad school so I came into this with more background knowledge, but it just wasn't my focus.

You mentioned ionic balancing, is that the same thing as base-cation saturation ratio? If it is, I will admit upfront that I am in the sufficiency level camp for that one, though I do honor our basic Ca:Mg ratio, as that came from research on natural water systems and everyone seems very keen on it.
 

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Again, this is something that comes out of the hydroponics world (I haven’t looked at terrestrial studies/opinions). I can’t say that it helps at all, but they think it does and it’s easy to do.

Ionic, or charge, balancing sounds cool, but I view it just as a means to take a look at your total fert package (including carbonates) and force yourself to try to get as close to a neutral charge as possible, while adjusting the individual elements. I run it through a calculator and then use it as the final screen for my nutrient package - mainly macros (all 6 of them).

I wouldn’t get too hung-up on it. I only use it as another tool to check for potential inequities as suggested by the hydroponics people. I think that the ppm ratios, in view of Mulder, is much more important. If you want to fool around with it, you can use this calculator: TDS Calculator
 
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