Salt mix from Sea Water (al-la Red Sea)

[Anonymous]

Can someone help me understand what happens when you evaporate the salt out of sea water and then try and make artificial salt mix from it?

I understand that it doesn't work well for some reason, but I can not for the life of me (and my high school chemistry education) understand why that would be. (aside from the easy ones, contamination, polution, etc) The chemistry forum appears to be locked, so I thought I'd post the question here.

 

[leftovers]

well you kind of answered your own question.

Number one, it wouldn't be artificial it would be an all natural salt mix since you aren't creating it from scratch.

Number two, it would contain EVERYTHING...all organics, pollution, trash etc.


You could pull in deep water saltwater and evaporate it to start with a clean salt medium. Usually though if i recall correctly the carbonates and magnesium are what get screwed over in the evaporation process. Leaving you with really nice salty water but bound up carbonates and magnesium as well. They aren't re-released back into solution for use by the animals.

I hope this helps others with stronger chem back ground im sure will pipe in

 

[Anonymous]

The issue with making salt mix from NSW is that, as leftovers kind of said already, is that the precipation is not reversible. This is due to the various ions in the NSW (Ca, Mg, etc.) that does not want to go back into the solution once they get out of it. This makes the "NSW-salt mix" deficient in several minerals, and have a white residues that won't dissolve no matter how much RO-DI you added.

The pollution/organic is only secondary to the reversibility issue.

 

[kaskiles]

So does room temperature or solar evaporation cause it to form calcite or something?

Maybe you could get that stuff to dissolve in your CO2 calcium reactor. Or use one of those planted tank CO2 systems in the water change mixing tank.

 

[brandonberry]

It actually forms gypsum. http://en.wikipedia.org/wiki/Gypsum

This happens due to evaporation causing a more concentrated slurry past the saturation point, thus causing the precipitation.


I think it may be able to be redissolved with a low enough pH , such as a calcium reactor, but this really isn't a practical way of making seawater.

 

[ron101]

This happens due to evaporation causing a more concentrated slurry past the saturation point, thus causing the precipitation.

Spot on.

Synthetic mix keeps those compounds separated. It's why you have to add synthetic mix to the volume of water that you want to make into marine water instead of the other way around (ie. add mix up to desired SG not dilute mix down to desired SG) because it will form precipitate.