for test kits, either SeaChem or Salifert. SeaChem's a little cheaper for basic marine test kit, and calcium kit. Salifert is arguably more accurate, and thus a little more expensive.
I started with Instant Ocean salt, but it NEVER would fully dissolve, and had low calcium, high alkalinity issues. I switched to Oceanic, and my corals look better now.
Former advisor and planted tank geek...life's moved on though.