Joy - when I was researching salts several years ago, I did run across some anecdotal evidence that some salt brands tend to promote cyano
more than others. I *think* it was the infamous "Borneman Salt Study" and if you Google that, you should find info on it.
There was a lot of criticism in the reefing circles about the study and I won't go into all that here, but it more or less focused on the somewhat non-scientific way the "study" was done. That's why I said above that the evidence was "anecdotal".
For me, there's more at work with cyano
than just excess nutrients - although having them doesn't help. I would think that pH and other water parameters play into it as well. And maybe some salts give you better parameters that tend to keep the cyano
at bay while others give you parameters that tend to promote it - given the same nutrient levels. Just me thinking out loud...
Your friend's experience with cyano
using your salt IS interesting. Does seem like an add coincidence, doesn't it. But again... the salt isn't really "causing" the cyano
- it can't. But I would think it's possible that it could make it easier to get a foothold if the water conditions are right.
Bavass - you're not going to find an answer to that question. There really is no "best" levels for those things. The "best" level for calcium itself is highly debated. Is it 380? 420? 500? 560? Everyone will have different opinions on that. And if you think super high calcium is a good thing, then your alkalinity is going to suffer. It's a trade off.
The "best" salt, in my opinion, is the one that you can easily get whenever you want, and works for YOU in YOUR tank.