I will try to clear up some of the misunderstandings in this thread. But I encourage any of you that would like more information about these salts to call me in the office at 413-367-0101. There are so many points that are being batted around here. I'm not sure I will be able to hit all of them in a post.
1) Bio Actif System salt and the Syn-Biotic Salt both contain dormant bacterial components. Some of these are nitrifying, de-nitrifying, and purple bacteria. In case purple bacteria is new to your understanding, it is responsible for the metabolization of very toxic hydrogen sulfide (a byproduct of anaerobic activity) to the less toxic sulfur and sulfates.
2) Bio Actif System salt is not specifically designed for low nutrient systems. It can certainly be used in that situation, but is also very helpful in systems that are not specifically low nutrient.
3) The only reason that the package states that Pro-Reef salt is recommended for use with calcium rectors, is that in some cases of very long term usage of calcium rectors, the system will experience a very slow and gradual rise in alkalinity. The fact that Pro-Reef is our lowest alkalinity salt version, makes it most appropriate for that application. It is not primarily designed for that, and it is a very "fine" point. I wish we would take that off the label. It is very often proven to be confusing for aquarists. Natural sea water average alkalinity is about 6.5 dkh. Pro-Reef salt is generally in the 7-8 dkh range. This is optimum for some species of corals. But that is the only relation to calcium reactors.
4) Bio-Actif System salt does NOT have more elements and minerals in it. It is not specifically related to 2 part addition. The label does not say that. So I'm not sure where that is coming from. All Tropic Marin salt version have the same amount of the same NSW 70 trace elements in them. The Bio Actif System salt, the Sy-Biotic Salt AND the Pro-Reef ALL have the exact same amount of calcium and magnesium in them. The Bio Actif System salt and the Syn-Biotic salts both have one additional point of dkh in the formula, but are otherwise exactly the same mineral parameters as the Pro-Reef salt.
5) For a zeovit system, I would use the Pro-Reef salt, not the Bio-Actif System salt.
6) Pro-Reef DOES NOT have less mineral or trace elements than Bio-Actif System Salt or Syn-Biotic salt.
7) A calcium reactor is NOT "recommended" for using any of our salts. It's just that the Pro-Reef salt, with its lower alkalinity, is most appropriate in systems that might have some influencing factor for raising the alkalinity.
I hope this information is helpful and clears up some of the misunderstandings. But, once again, typing is not my forte. So the best way to get the most detailed information is to just give me a call in the office and talk it through.