Dumb Question - Can Salt Go Bad?

[skibum1681]

Last week i made a tub of RO/DI to make some salt water for a water change on my 40 FOWLR. My salt was kinda hard so i broke it up & went about my business mixing my water. I put my power head & heater in the tub till the next day. I checked the temp & S.G. which were right where they needed to be (80deg & 1.024). I started wondering if there was a problem cuz there was a white film on top of the new water. I ran my tests & everything looked good so i went on with my water change. I had a gallon or so left over so i went and dumped it out. When i dumped it out i noticed quite a bit of something (salt???) that didnt disolve. Its been bothering me all weekend but the tank looked fine. Now today i'm seeing that film on top of the water.

I dont have an overflow and just run a HOB aquaclear filter.

Has anyone ever seen this? Am i worrying over nothing?

Oh yea, Red Sea Salt.

[Roy G. Biv]

I had a similar experience. I just ignored it. I didnt notice anything off either.

[JamesJR]

Your salt mix is probably not any good any more. This could easily be confirmed by testing the Calcium, magnesium and alkalinity of freshly prepared batch of water.


The mix itself doesn't really go bad unless it gets exposed to moisture. When this happens the Calcium and Bicarbonate that are present in the salt precipitate out and form a solid when there is any trace of moisture in the bag. There really isn't any way to get it to redisolve easily and you are better off not using the salt mix.

You have to really do two things when you make seawater that are not really emphasized on the directions.

1). The mix has to be kept super dry otherwise some precipitates will form and the composition of the water you make will be off.

2). When you mix it with the water you need lots of vigorous flow. The salt mix should never be able to setttle out while you are mixing it, otherwise precipitates will form.

[Sk8r]

Buffer goes bad. In so far as salt mix has buffer in it, it would lose that component.

[Aquarist007]

<a href=showthread.php?s=&postid=13360121#post13360121 target=_blank>Originally posted</a> by Sk8r
Buffer goes bad. In so far as salt mix has buffer in it, it would lose that component.

+ one on that. Magnesium can precipitate out of it easily too.

[fatdaddy]

I use instant ocean and always get a precipitant. I've just ignored it, but I'm careful to not add it to the tank.

I use a 5 gallon pail that seals. When I open up a new thing of Nori, there is a silica package that absorbs moisture. I open up the pail and throw it in. It keeps the salt nice and dry. (Hint: put month/year on it, so you can throw out the old ones when you dip into a new batch of salt. )

I know divers use these in their camera case to keep it from fogging up, so you can buy them. I'm not sure where. I find it's just easier to dive in warm water. :)

[skibum1681]

Thanks for the responses. That salt will get tossed. I will keep the new salt air tight & start saving the silica packets from everything. I uesed to save them for cell phone accidental dunks.