David Hillyard wrote:
Thanks for the advice. I have now added the extra salt and the SG is up to
1.025.
Ca is now 375, Mg 1170.

My lfs tested a small amount of my salt in RO in case I had a bad batch but
the Ca and Mg readings were a lot higher for him. The test kits I'm using
are brand new and not contaminated. LFS has confirmed my low readings are
accurate.

Having done a little research on the web it seems others have had a similar
experience. I have no substrate at this stage but my lfs doesn't think that
would make any difference anyway.

Would it be a mistake to add live rock with low readings and would it be OK
to add magnesium to bring the levels up or would this cause more problems
later?

Any help is greatfully received, so thanks to GrimReaper.


Just so you know those values are a little low but they are in the safe
range. You can add your liverock without any problems. It is actually
not uncommon for freshly mixed sal****er to be low. You could add a
little bit of epsom salt to the tank to bring up the mag a little, but I
would not worry about it if it was my tank. Once you start dosing your
calcium/alk suppliments you will bring your Ca in line.

Kim
www.jensalt.com