A reactor is a big plus for a tank.. Espically a larger tank. The addition of chemicals has it's drawbacks as does a reactor. But, a reactor does a better job of maintaining calcium and other levels in the tank since it is a constant feed. There are other advantages also. A more stable PH can be reached with the use of one. The media also contains strontium and magnesium, and other minor elements for a tank. Most tanks (larger ones) that have a high demand for calcium ie: Stonie tans: use reactors. In a smaller tnak and more soft corals they would really not be a nescitiy.
But, there is always a flip side. The less maintance and dily routine of a reactor is a huge plus.! The UP front cost is what drives most away. 150 is probably just for the chamber. Add a CO2 bottle, regulator, needle valve tubig...etc... and your cost will go up.
IMO, A reactor does a very good job at maintainig calcium and will raise it in a tank over time to a desired level. You control the amount by regulating CO2 levels.
