Shelf life of ASW mix?

[ScottT1980]

I posted this elsewhere, but thought I would get some more opinions. I have a bucket of Reef crystals from someone that has been out of the hobby for quite some time. It is still factory sealed, but perhaps 4-5 years old. What do you think?

TIA

Take er easy
Scott T.

 

[NaH2O]

Hmmm, Scott - good question. I would think that since it is still factory sealed, then it is probably alright, as long as no moisture got into it. However, I imagine there is probably some settling. One thing I'm not real sure of, is whether the ingredients of a salt mix would break down over time. For instance, a box of baking soda or baking powder is only good for so long in your cabinet, right? I've tried to make cookies or cake before and had issues (not because I'm a bad cook - I'm actually quite good)

*moving to the chemistry forum for Collin to have a peek

 

[cwcross]

I think the salts are still good. I would suggest mixing the salt well before using. Also, it may be that the alkalinity may need to be adjusted more than usual. However, I doubt this will be a problem.

Nikki's point is valid about the carbonates and bi-carbonates though. These things can gain or lose CO2 to interconvert to one another. Because of this over time, the properties of baking soda can change. However that being said, in water CO2 from air will equilibrate as it wants. The other salts are largely inert and will change on geological time scales. The only other factor Nikki pointed out is water. If the salt is all caked up it will look ugly and be hard to mix up. This isn't really a problem for the final state in the aquarium, it will just make it harder to mix up.

All in all, I would think that it should be no problem to use the salt. Just mix up well and run normal tests before using it in the tank.

Sincerely...Collin