I wonder...if this box was actually reef crystals salt, and was packaged as regular Instant Ocean?
The reason I am curious is, not only are the parameters what I always tested with IORC, but I now have brown residue over my powerhead, and my mixing container that I never had previously before I started with this box. The parameters I'm testing at are almost identical to what I was testing using Reef Crystals.
It's very possible. I bought two boxes for quick water changes and I do get a brownish ring at the top of the water line in my brutes... I've only tested Alk, haven't tested the other two.

