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Form of Calcium Dose

FishWorks

Member
Joined
18 Dec 2016
Messages
50
Location
Philippines
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
 

X3NiTH

Member
Joined
13 Apr 2014
Messages
1,244
CaCl2 precipitates after you add it to your aquarium

Only if you exceed the maximum solubility of Calcium compounds already present in the receiving water.

I mainly use the Carbonates of Calcium and Magnesium for water hardening, I can supplement with Calcium and Magnesium Chlorides if need be or the Sulphates of both, or a careful blend of the whole lot.

Calcium Nitrate is the mineral to watch out for if your looking for precipitate problems, still useful as part of a blend but I wouldn’t mix it with Magnesium Sulphate in a dosing solution because you’ll end up with Calcium Sulphate precipitating out of solution rendering the mix useless.

The salts you should use are the ones that are most convenient for you, once in solution it doesn’t matter to the plants where the ions came from.

:)
 

FishWorks

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Thread starter
Joined
18 Dec 2016
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50
Location
Philippines
Only if you exceed the maximum solubility of Calcium compounds already present in the receiving water.

I mainly use the Carbonates of Calcium and Magnesium for water hardening, I can supplement with Calcium and Magnesium Chlorides if need be or the Sulphates of both, or a careful blend of the whole lot.

Calcium Nitrate is the mineral to watch out for if your looking for precipitate problems, still useful as part of a blend but I wouldn’t mix it with Magnesium Sulphate in a dosing solution because you’ll end up with Calcium Sulphate precipitating out of solution rendering the mix useless.

The salts you should use are the ones that are most convenient for you, once in solution it doesn’t matter to the plants where the ions came from.

:)
Thanks, I think I will use the CaCl2 then.👍
 

three-fingers

Member
Joined
15 Sep 2008
Messages
390
Location
Scotland
CaCl2 is great :). I use a DIY liquid made with it sometimes, just for peace-of-mind that my snails/shrimp/triops have enough bioavailable calcium in my soft tap water - although it's probably not needed at all.

Many years ago people used to reccomend Kent Marine Liquid Calcium, "Snail Strong" liquid calcium and many others similar for this, but now it's just as easy to buy a small amount of dry CaCl2 from ebay and mix your own at a fraction of the cost.

I've also tried calcium nitrate but never use it as I've found potassium and magnesium are way more important for plant growth - so I mainly use potassium nitrate and magnesium nitrate.

I find the best way to provide calcium to aqaurium plants is to add sea shells/limestone containing rock to the tank/filter - it starts to dissolve as soon as the water drops below 7.0 (most tanks do when the lights go out) and provides both the required calcium and as a bonus - carbonates - which can provide a carbon source for certain obligate aquatic plants like vallis, Egeria, hornwort etc.

What is your goal with adding additional calcium though?
 

FishWorks

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Thread starter
Joined
18 Dec 2016
Messages
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Location
Philippines
I
CaCl2 is great :). I use a DIY liquid made with it sometimes, just for peace-of-mind that my snails/shrimp/triops have enough bioavailable calcium in my soft tap water - although it's probably not needed at all.

Many years ago people used to reccomend Kent Marine Liquid Calcium, "Snail Strong" liquid calcium and many others similar for this, but now it's just as easy to buy a small amount of dry CaCl2 from ebay and mix your own at a fraction of the cost.

I've also tried calcium nitrate but never use it as I've found potassium and magnesium are way more important for plant growth - so I mainly use potassium nitrate and magnesium nitrate.

I find the best way to provide calcium to aqaurium plants is to add sea shells/limestone containing rock to the tank/filter - it starts to dissolve as soon as the water drops below 7.0 (most tanks do when the lights go out) and provides both the required calcium and as a bonus - carbonates - which can provide a carbon source for certain obligate aquatic plants like vallis, Egeria, hornwort etc.

What is your goal with adding additional calcium though?
Unfortunately, my Calcium comes in at 1.6ppm from the tap. :(
 

three-fingers

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Joined
15 Sep 2008
Messages
390
Location
Scotland
That is quite low! But do you have any indications of calcium deficency, are you wanting to prevent moulting issues with freshwater shrimp, or something else specific?

If it's just for plants and you have soft water it's probably easier and better for your plants to just chuck some shells or other calcium carbonate containing material into your filter or substrate, which saves faffing around with measuring, dissolving and frequently dosing chloride salts.

As mentioned, I use CaCl2 as well, but mainly just for peace of mind with my soft tap water (<10ppm Ca), or if I'm using RO/rain water (0ppm calcium) and trying to avoid shedding issues in certain invertebrate species that benefit from soft water like triops, or improve fragile shell condition in aquatic snails. I personally wouldent bother with it just for plants, I've used RO without adding calcium specifcally and been fine even with high light and CO2 :).

Potassium, on thier other hand, I'm constantly having to add extra for the plants lol.
 
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