Calcium Chloride Dihydrate

First let me mention this, although you might already know

Chlorine - Cl, chemical element
Chlorine gas- Cl2 --- toxic, keeps water clean from bacteria
Chloride -Cl-, anion of Cl, like in sodium chloride ( table salt)

CaCl2 is not considered toxic or an water disinfectant. I used to use CaCl2*2H2O for my remineralization but did not see any major change in plant growth. The ion is transportable in plants and in terrestrial plants it can cause problems in saline conditions , however aquatic plants don't 'pump' water from the roots to the leaves where it evaporates so this alone changes the dynamics of accumulation. Far as I know, fish also won't be impacted from 5GH coming from CaCl2*2H2O

 

I did not see any side effects to plants or fish when I was using it in my aquarium. I have not tested it against every plant or fish species in the hobby to be able to make blank statement, but I feel reasonable sure in using it again in any of my aquariums. I also think many of the shrimp targeted mineralizers contain chloride salts instead of sulphate salts.



The I am adding:... field in your configuration is now for the mass of substance you are adding to the bottle, not the aquarium.
You have mL selected in the calculator. Select mg for solids. Use mL only for liquid solutions of fertilizers.

It also looks weird to me that you are making 100mL of solution and one dose is 90mL.

In my opinion, it is easier to dose solid, select 'dose to reach a target' and put the Ca in ppm target. Play with it until you get the desired GH from Ca. Add the salt to the water during a water change (of course only calculate for the volume water changed, not the entire aquarium)

 

Hi again,

I imputed your numbers into the rotalabutterfly.com calculator, see the attached image.

The number given by the rotala calculator is correct because it takes into account the hydration state of CaCl2*2H2O( Ca 27.26%). The other calculator is wrong , despite listing the correct compound, it uses the wrong % CaCl2 (Ca 36.11%). If you do the math you will see that the difference in % is exactly the difference between 16 and 12pm Ca.

2 more things. It is unlikely you will be able to dissolve so much CaCl2*2H2O in 100mL water. The solution will become saturated and some CaCl2 will remain at the bottom of the bottle un dissolved. Increase the volume by a factor of 10, ie 1000mL

The second is that dosing 1.75mL at home is very likely to be inaccurate. Much easier to work with 10mL or 15mL doses. Just change dose size and amount added.

If you need any clarification with the math or help, let me know.

 

Hi AgMa,

solubility specs without a temperature attached to them bother me, based on other sources it's likely that the 97.7g/100mL is not at 20-25°C (room temperature). Oxychem has a nice phase diagram available in the description ( https://www.oxy.com/OurBusinesses/Chemicals/Products/Documents/CalciumChloride/173-01791.pdf )
Depending on the granulometry of your salt, it can be that 97.7g of salt alone will be more than 100mL. I know for mine 5mL are about 3.7g. Nevertheless, try it out see if it remains dissolved but make it in a larger container so you can add more water if needed.

By insulin syringe you mean a 0.3mL or larger like 1mL ? You would need to draw twice at least with the 1mL, each draw has a certain error. With small volumes air bubbles, what remains in the needle, angle of view, etc all are sources of error. I really see no reason to work with such small volumes when water is cheap but it is your tank and CaCl2 dosing does not have to be spot on in normal aquariums

The dose size is the final solution volume you want to add to the aquarium.

The "I am adding ..." is the mass of salt to be added to the bottle.

PS. Just to be sure Container size should be water+salt volume

 

Hi AgMa,

The way you should prepare solutions is :

• Prepare marked container - clean and dry.
  
• Weight salt
• Add salt to the container
• Add water to the desired volume
• Mix until completely dissolved and nothing settles back on the bottom
  
• Transfer to the long term storage bottle

The way the calculations are done is that the "desired volume" is the total volume (water+salt). This is marked in the calculator with "Container size". So in the case you mentioned above, "Container size" 100mL means you will end up with a total volume of solution of 100mL. If the salt volume is about 50mL you would need to add ~50mL of water to it. This is quite a common mistake and if solutions are not very concentrated it does not have a big impact ( like 10mg in 1L). Yours is a concentrated solution.

This stems from the classic definition of concentration= mass solute / (mass solvent+ mass solute). Adapted to our needs concentration[ppm]= mass solute[mg] / (volume solvent+volume solute)[L]

Let me know if you have any questions.

 

Positive. You can double check my math. These are the steps/math rotalabutterfly.com does for you.

what we know:
Aquarium volume: 35L
Solute: 90g CaCl2*2H2O
Solution volume: 100mL
Volume of dose: 1.75mL

1) Find mass percent of Ca from CaCl2*2H2O based on atomic weight: 40.1 / (40.1+35.5*2+4*1.0+2*16.0)=40.1/147.0=0.273
2) Find theoretical mass Ca in our solute : 90*0.273=24.5g Ca2+
3) Find conc of Ca in solution : 24.5(g) / 100(mL)=0.245g/mL Ca2+
4) Find how much Ca one dose adds: 1.75(mL)*0.245(g/mL)=0.429g Ca2+
5) Find Ca conc in the aquarium after one dose: 0.429(g) / 35(L)=0,01227g/L=12. 27mg/L =12.27ppm

Reference: 1g=1000mg ; 1L=1000mL; c=m/V where c - concentration, m- mass solute, V- volume solution.
Rounding errors may be present.

As you see the math when using 100mL of total solution volume leads to the same value as rotala's calculator ( see image above).

If you know the total volume of solution you ended up with you can recalculate using that and see how much you add now, ie just replace 100 in step 3) with whatever volume in mL you used. You can also increase the dose to match your original targets. Like I said the adjustments are likely to be minor if the solutions were dilute.

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You can also think of it this way :
So I end up putting 90g in 100mL. If I take 1.75mL from that solution, i take the 1.75/100 part. This means that each dose is like adding 1.75/100*90=1.575g CaCl2*2H2O. Put this number directly in rotalabutterfly.com or apply step 1) and 5) from above and you will get ....12.27mg/L

 

Yes the screenshots you added are correct. Add 41.08g of CaCl2*2H2O to your mixing container, add water until the 100mL mark . 5mL from this solution will add 16ppm Ca to a 35L aquarium . I think this amount will fully dissolve

 

Yes, around that ... with salts it's not easy to estimate the actual salt volume... you have airgaps between the grains and air trapped inside the grains, that's why I said add water until 100mL mark. If you know for sure the container is 100mL then fill the container up.