Old IO Salt - Safe to use for cultures?


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Dec 23, 2015
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I recently bought a large lot of saltwater supplies from someone who was clearing out their basement, and with it came a few boxes of IO salt of unknown age. I didn't really plan on using it but part of the deal was I take everything, so into the shed they went. I recently started culturing phyto and thought maybe I could use it for the phyto water, so I busted out a pack and went to mixing it up. Even though the bag was sealed, some moisture had gotten into the salt and it was a bit clumpy and slightly moist. I still mixed it, but there is a bit of residue at the bottom of the bucket that despite agitation will not dissolve into solution. My theory is that the moisture facilitated some chemical reactions and formed some calcium carbonate or other similar solid, but this is just a guess and I have no idea what it actually is. My question is, if I adjust to correct salinity, and disinfect the water with bleach before use like I normally do, is this OK to use for culturing purposes? I have a ~200g system and rarely add more than 1L of cultured phyto at a time.

Have you ever had problems with zoanthids "melting" in your tank?

  • YES but only with certain zoanthids

    Votes: 80 40.4%
  • YES with a lot of different zoanthid types

    Votes: 46 23.2%
  • No not at all

    Votes: 47 23.7%
  • I don't keep zoanthids

    Votes: 23 11.6%
  • Other (please explain)

    Votes: 2 1.0%
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