# Cacl2 + MgSO4 in the same bottle ?



## eminor (6 Oct 2022)

Hello,i have hard time to mix cacl2 + epsom salt in the same bottle, i'm bad at chemistry but i found that the reaction would produce CaSO4 + MgCl2, is that correct ?

If i'm not wrong CaSO4 is insanely hard to dissolve in water, that's why i can't make it work ? i might be wrong


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## dw1305 (6 Oct 2022)

Hi all,


eminor said:


> i have hard time to mix cacl2 + epsom salt in the same bottle, i'm bad at chemistry but i found that the reaction would produce CaSO4 + MgCl2, is that correct ?
> 
> If i'm not wrong CaSO4 is insanely hard to dissolve in water, that's why i can't make it work ? i might be wrong


You <"are right">.


> _..... 0.26 g/100ml at 25 °C (dihydrate) (CaSO4.2H2O)_


Have a look a the <"solubility rules chart">. If you add salts, where their ions would combine to end up in the green (or pink) boxes, you will get that compound precipitate.

You can see that ions with a valency of one ("monovalent") are all soluble, so potassium (K+), nitrate (NO3-) and chloride (Cl-) etc will, almost always, remain in solution, but for ions with higher valency (Ca++, Mg++, PO4--- etc) the situation is much less clear.





cheers Darrel


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## eminor (6 Oct 2022)

Amazing, thank you so much


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## MichaelJ (6 Oct 2022)

Hi @eminor I use CaSO4 and MgSO4.  For pre-bottling CaSO4 In a small bottle it’s impossible to dissolve so if you insist in pre-bottling your GH remineralizer CaCl2 is a good option. However, if you pre mix in a larger  container during WC CaSO4 is not a problem at all unless you target a very high Ca ppm.  I’d much rather use CaSO4 that than use CaCl2. I don’t think adding chlorides is good in the long run and it also carry a much higher footprint in terms of TDS.

The solubility of CaSO4 being 2.4g/l  you literally have to target an astronomical GH level in your solution to get into trouble.

Cheers,
Michael


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## eminor (6 Oct 2022)

MichaelJ said:


> Hi @eminor I use CaSO4 and MgSO4.  For pre-bottling CaSO4 In a small bottle it’s impossible to dissolve so if you insist in pre-bottling your GH remineralizer CaCl2 is a good option. However, if you pre mix in a larger  container during WC CaSO4 is not a problem at all unless you target a very high Ca ppm.  I’d much rather do than than use CaCl2. I don’t think adding chlorides is good in the long run and it also carry a much higher footprint in terms of TDS.
> 
> The solubility of CaSO4 being 2.4g/l  you literally have to target an astronomical GH level in your solution to get into trouble.
> 
> ...


i'm confused, i though chloride was safe at those level ? i add 60 ppm Cl a week, too much ?


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## MichaelJ (6 Oct 2022)

eminor said:


> i'm confused, i though chloride was safe at those level ? i add 60 ppm Cl a week, too much ?


No, for targeting 34 ppm of Ca, 60 ppm of Cl is not harmful as such (I believe many members here use CaCl without issues) just completely unnecessary- I actually don’t know what the long-term harmful levels would be, but I don’t see how 60 ppm could be beneficial either.  For the same Ca target (34 ppm) using CaSO4 you get 27 ppm of S… also unnecessary, but your adding way less of something your tank absolutely don’t need.   Hope that makes sense.

Cheers,
Michael


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## dw1305 (7 Oct 2022)

Hi all,


MichaelJ said:


> No, for targeting 34 ppm of Ca, 60 ppm of Cl is not harmful as such (I believe many members here use CaCl without issues) just completely unnecessary- I actually don’t know what the long-term harmful levels would be, but I don’t see how 60 ppm could be beneficial either. For the same Ca target (34 ppm) using CaSO4 you get 27 ppm of S…


I use a <"dash of tap water"> to add calcium (Ca++). In this case the dissolved CaCO3, becomes Ca++ and two HCO3- ions (1 : 1 dGH / dKH). 


dw1305 said:


> I'll be honest I would just add a small amount of tap water as your remineralising agent, you already have a conductivity (TDS) meter and I'd just aim for somewhere near 100 microS, and your water is "remineralised".
> 
> If you use a conductivity reading (rather than adding remineralising salts) it doesn't matter if your tap water varies a bit throughout the year. I'm <"pretty slap-dash"> but @Geoffrey Rea is a proper aquarist and <"that is what he is doing">.


If I wanted to add calcium without adding any carbonate hardness (dKH)? I'd just dry dose a minimal amount of either CaCl2.2H20 or CaSO4.2H2O.

As @MichaelJ says you are adding two chloride ions (Cl-) for every calcium (Ca++) ion with calcium chloride (CaCl2), because the cation charge (Ca++) and anion charge (2 Cl-) must always balance.

cheers Darrel


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## Oldguy (7 Oct 2022)

dw1305 said:


> I use a <"dash of tap water">


Never understood why people don't use tap water for remineralising, its cheap and delivered to the door. (some will have very soft water and want to keep hard water fish so for them there is a good reason)
As for soft water it rains most days. Gave the butt its annual clean out, well it had developed a pin hole leak, it got replaced. Full and overflowing in two days.


dw1305 said:


> Have a look a the <"solubility rules chart">


Thanks for posting the chart, very useful. Copied and filed away.


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## dw1305 (7 Oct 2022)

Hi all,


Oldguy said:


> Never understood why people don't use tap water for remineralising, its cheap and delivered to the door.


Yes, <"simple,  easy etc.">. I've even got a map to go with it, and I just assume <"all the dGH"> is calcium (Ca++). I'm always going to add magnesium (Mg++) with my fertiliser, so I don't need as a remineraliser.





Oldguy said:


> some will have very soft water and want to keep hard water fish so for them there is a good reason


Soft water makes it fairly easy, you can just add a salts mix to mimic <"whichever of the Rift"> (or Mexican) Lakes you keep fish from. Also if you want to <"decouple dGH and dKH"> you need to use an alternative to tap.


Oldguy said:


> Thanks for posting the chart, very useful. Copied and filed away.


Yes, it is useful. I use off and on with the students and once or twice even with members of staff, who should really know better.

cheers Darrel


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## MichaelJ (7 Oct 2022)

Oldguy said:


> Never understood why people don't use tap water for remineralising, its cheap and delivered to the door.


Ideally yes - if you know your tap water well. If not, the downside of mixing with tap is that your really not much in control in terms of what your getting - Yes, you can target the desired hardness, but the exact Calcium and Magnesium amounts, the amounts of Nitrates, Phosphates, Copper, Zinc, Silicates, Chlorine (just to name a few) and possible pollutants remains largely unknown unless you have a very reliable up-to-date water report.

Cheers,
Michael


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## Oldguy (8 Oct 2022)

MichaelJ said:


> if you know your tap water well.


Yep. Very reliable local water source & reliable water company analysis. Water source, tap water, rain water and treated sewage all go to the same drainage catchment. Do we really need water that never varies. In nature rivers run low in summer and high in winter and 'coloured' in localised heavy rain.  We add nitrates, phosphates, copper, zinc and more as our fertilizer mix. Estimated Index is estimated.

I am of the view that we have fallen for RO water and in reality it is just another source of income for our retailers. I do buy the odd 5litres, its cheaper than deionised water for the steam iron. Though lately I just spray tap water on my ironing and use a moderate temperature iron. The spray bottle is a reused bottle that contained bathroom/kitchen cleaner. It was cheaper to buy a spay bottle with 'stuff' in it than buy an empty spray bottle.

May be I have been fortunate in where I lived as regard tap water quality, then I do live in the UK (hardness varied, both total and temporary -you didn't need an analysis- could you get a lather with soap and did the kettle need descaling). Now I think water is blended for large conurbations. I can also remember when in France or Spain you did not drink the tap water.


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