Reef Chemistry Question of the Day #24 Calcium Concentration

[Randy Holmes-Farley]

Reef Chemistry Question of the Day #24

Which of the following possible additives has the highest concentration of calcium in it?

A. RO/DI water saturated with calcium carbonate
B. RO/DI water saturated with calcium hydroxide
C. RO/DI water saturated with calcium oxide
D. RO/DI water with 10 grams/L of anhydrous calcium chloride added
E. RO/DI water with 10 grams/L of calcium chloride dihydrate added
F. Natural seawater at 35 ppt salinity

Good luck!
















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[Randy Holmes-Farley]

No takers yet?

 

[mike007]

My guees is f. Lol

 

[DFW]

All that I can do is guess! C?

 

[AmnezyaDarkside]

I would say f

 

[acromancer]

I would say B because calcium Hydroxide contains the most calcium by dry wight.

 

[reggaedrummin]

I'm curious!

 

[leptang]

E is my guess

 

[miamiangler]

I use NSW so I am going with F.
430ppm collected an hour before high tide .

 

[spspirate]

hmmmm.........B

 

[Randy Holmes-Farley]

This one turned out harder than I thought.

Here are the approximate values for calcium in each of those solutions:

A. RO/DI water saturated with calcium carbonate (10-20 ppm, depending on whether atmospheric CO2 is allowed to enter)
B. RO/DI water saturated with calcium hydroxide (~820 ppm)
C. RO/DI water saturated with calcium oxide (~820 ppm)
D. RO/DI water with 10 grams/L of anhydrous calcium chloride added (~3,600 ppm)
E. RO/DI water with 10 grams/L of calcium chloride dihydrate added (~2,730 ppm)
F. Natural seawater at 35 ppt salinity (~420 ppm)

So the answer is: D. RO/DI water with 10 grams/L of anhydrous calcium chloride

 

[Randy Holmes-Farley]

I would say B because calcium Hydroxide contains the most calcium by dry wight.

That's true, but calcium oxide and hydroxide are limited by fairly low solubility. That why folks using limewater/kalkwasser may not be able to use enough, even when replacing all evaporated water with limewater.