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Discussion Starter · #1 ·
Which of the two, CaCl or CaSO4, do you think will have a negative effect on a heavily planted tank with inverts?

From everything that I have read, Sulfates do not play a role negatively on flora or fauna. So then, which would you choose to does if you had to raise your Ca levels?
 

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CaSO4 is a PITA to dissolve. It's plaster. CaCl is by far easier to dissolve but do so only out of the tank as dissolution is exothermic while with most other salts it's endothermic. CaCl is also harder to store as it is hygroscopic and will take in moisture at an alarming rate making it hard to store unless you immediately turn it into a solution. Why don't we use CaCl more? I don't really know. The amount of Cl- you end up adding from CaCl is negligible.
 

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Discussion Starter · #3 ·
Jeff,

Thanks for the reply. I ran a little experiment using CaSO4 and found that when adding small amounts, 0.2500g – 0.0500g in to 250ml DI water, the amount of Ca and Sulfates that became present were fairly large numbers.

Using 250ml DI water I added 0.05g Calcium Sulfate and mixed the solution for 10 minutes on a stir plate. I then tested the Calcium and Sulfates.

CaSO4 Ca (ppm) Sulfate (ppm)

0.05g 132 70
0.10g 252 180
0.15g 384 270
0.20g 492 370
0.25g 616 440
 

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The problem is that you'll have to add about 10ml solution with something like that. I personally just add an arbitrary solid amount to the tank (~1/2-1/4 tsp per 20 gallons of water biweekly.) I've been using CaSO4 since I ran out of CaCl and I'm not in the mood to go buy it when I have tons of calcium sulfate. So I would suggest using CaCl with dosing via liquid and then CaSO4 when dosing with solid. As for safety for shrimp. That would depend. Some shrimp are sensitive to hard water...but I would assume either or is fine.
 

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Discussion Starter · #5 ·
Are you using Di/ro or tap water? What purpose are you adding the CaSO4 if you don't mind my asking?

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I had RO water and was dosing slightly more Ca than what I just said. Now I use tap and use less Ca. I forgot to mention that I mix mg. with the CaSO4 so you might want to halve those amounts if you add pure CaSO4. Why? It's because my plants are calcium hogs and the current set of plants I have don't particularly like acidic water (L. brevipes & arcuata) which my heavy CO2 additions and substrate tend to cause.

With this regimen I've gotten great growth and by no means is it fit for everyone. This is just the routine I have come up with that suit my combination of plants and water and light.
 

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Discussion Starter · #8 ·
Have you thought about adding a slow drip of weak CaOH? Do you by chance know what the Carbonate levels are at?
 

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Using kalkwasser sounds like a bad idea unless you really need a crud ton of calcium. Even reef tanks won't need it unless it's loaded with SPS. I think reconstituted RO is a better idea. I don't know what my concentration is anymore of carbonate. It's such a wonky measurement with CO2 injection and all.
 

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Discussion Starter · #11 ·
The hydoxide ions will contribute to the alkalinity and the pH of the tank as well.
Thats is what I was thinking. If the hydroxide will counter act the addition of the CO2 in the tank. This will also allow the Ca to be used by the plants. I have never worked with Kalkwasser but the CaOH that I do work with,it is easy to make up a weak solution and then add to a larger solution (the tank). But I would think that a drip system would be better as to not make huge pH swings between the CaOH and the CO2.
 

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If you want to prevent pH swings from co2. Try addition of HCO3- in the form of baking soda. Do you only want to increase pH and GH though? I'd just toss some crushed coral in the filter and call it at that.
 

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Discussion Starter · #13 ·
Adding to much HCO3 will increase the pH. Baseline pH of Baking Soda is ~ 8.02 if I remember right. I was just trying to think of a way add Ca while keeping pH swings in check. Sort of trying to kill two birds with one stone.
I tend to forget the KISS approach.
 

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Discussion Starter · #14 ·
I was reading through the ingredients of equilibrium by seachem, it states that it is 11 percent calcium sulfate.
I just thought that was interesting in deserve to be posted since it pertains to what we were talking about.

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