There are a bunch of products like this. Most (like Salifert All in One) are Calcium acetate, and the acetate, when metabolized, produces the alkalinity (see below).
The Tropic Marin product is probably calcium formate (which is very like acetate (CH3CO2-) but a little smaller of an organic molecule (CHCO2-)).
I discuss calcium acetate here:
The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION
One-part balanced additive systems: Calcium Acetate
Calcium acetate is a product that has gotten relatively little publicity despite its apparent ease of use and the commercial availability to aquarists. In some ways it is similar to the combination of limewater and vinegar. When dissolved in water (fresh or salt), you have calcium ions and acetate ions. The acetate is rapidly metabolized by tank organisms to form bicarbonate, carbon dioxide, and water:
CH3CO2– (acetate) + 2 O2 → HCO3– + CO2 + H2O
This equation suggests that pH of such tanks may stay near the low end of normal, because of the excess carbon dioxide, but the practical experience of people using calcium acetate suggests that this is not a big concern.
Calcium acetate will also facilitate the growth of bacteria and the reduction of nutrients in systems, similar to that with folks dosing vinegar or vodka for that purpose. It will also facilitate conversion of nitrate to nitrogen gas (N2) in anoxic regions of live sand and rock by providing the carbon source necessary for the process. The equation below shows the process that could take place:
5 CH3CO2– (acetate) + 8 NO3– → 10 CO2 + 4 N2 + 13 OH– + H2O
One of the sources of calcium acetate available to aquarists is Salifert’s All in One (a product that also contains some strontium, amino acids, and some trace elements). It is a liquid product that can be poured directly into a tank with no immediate concerns about pH. The current version of their commercial product is 250,000-mg/L calcium acetate, so it contains the equivalent of 3,160 meq/L of alkalinity. This product sells in the US for about $45/L. Consequently, it costs about $14 per thousand meq/L of alkalinity. That price makes it very expensive for an aquarium with a large demand for calcium and alkalinity, but the zero equipment cost (unless you automate it with a dosing pump) makes it attractive for small aquaria, especially nano-reef tanks.
I have no information on the purity of the material, or the exact nature of the “trace elements” in it. Everything in the bottle will be delivered to the tank. It poses no unusual safety concerns. The upper limit to how much calcium and alkalinity can be supplied to a tank in this fashion depends on two factors. If the metabolism of acetate is rapid and the dose is very high, oxygen might be depleted. If the conversion is slow then acetate can build up in the tank (not itself a significant concern except perhaps at very high levels where it might confound an alkalinity test). Habib Sekha of Salifert has indicated that using the doses recommended on the bottle will not lead to either of these issues being problematic.
Overdosing is not expected to be an unusual problem, but if one makes significant additions in this fashion, the alkalinity will take time to show up completely in the tank because the acetate takes time to be metabolized. Consequently, I’d wait a day after adding it to measure alkalinity. Calcium measurement won’t be similarly impacted. Tank salinity will not increase over time using calcium acetate.
