Bucket of salt hard as a rock.

[ckusnierek]

Well yet another bonehead thing I have done. last week end when I did my WC I left the lid off my bucket of IO. Now (from moisture) it's hard as a rock. I mixed up 5g and it seemed fine. I just have to use my hands to crumbel the shunks of salt when mixing. Will that affect the salt mix?

[crvz]

I don't think it's too big a deal, but I've never experienced it in large doses like you may be. Test for alk and calc and pH before using it. if those are within the norm, I imagine it would be fine (I would be afraid of precipitation).

[tdwyatt]

Originally Posted by ckusnierek

...when I did my WC I left the lid off my bucket of IO. Now (from moisture) it's hard as a rock.

...Will that affect the salt mix?

There is actually a reaction that occurs when the calcium chloride absorbs enough moisture to do this. It drives the reaction at high concentration that converts sodium bicarbonate in the presence of the CaCl2 into calcium carbonate and sodium chloride. The calcium carbonate formed in this manner is high above the max solubility for calcium carbonate in water and will gather as the precipitate seen in the bottom of the mixing vessel when such clumped salts are used. Brines mawde from these salts will be at varying degrees of calcium and alkalinity deficiencies, based on how hard the clumps are (= how much water was absorbed from the atmosphere to allowfor the two chemicals to react). The hydration reactions will not be limited to calcium as the cation, but it is the major problem in that it has the lowest solubility, and will preferentially bind to carbonate under the circumstances.

Such salts will still make salt water, but it is not seawater in that it will no longer be of conservative proportionality. Use it for washing rocks or cleaning out sumps, etc at 35 PPT, otherwise, it is trash. To demonstrate, take some of the salt in question and make a batch of ASW up to 35 PPT @ 80degrees F and test for alkalinity and calcium, you may be surprised. At one time, many aquarists were using clumpy salts to make their ASW, then complaining about what poor quality the particular brand of salt was they used to make their ASW because it was "so low in calcium and alkalinity" compared to seawater...


How much off from seawater will depend on how "wet" the salt actually became, so humidity, length of exposure, and air exchange around the open container will all play a factor in the final loss of calcium and alkalinity when forming Calcium carbonate. Approx solubility of CaCO3 in FW is about 500mg/liter depending on temp, pH, and other salts in the water, literally a drop in the bucket (think of how big a 500mg tylenol tablet is, and remember that half of the tab contains buffers, tablet binders, and excipients in addition to the acetaminophen...), and the rest of the product will be precipitated out in the bottom of the bucket.

[Twitterbait]

good to know. i always wondered that. i used my clumped salt to cook my rock.