I have used ESV B-Ionic for a few years, and keep it on hand now that I use a calcium reactor. Just about any online aquarium supply will have it. Warner Marine Research 2 part has been suggested as being very high in quality if harder to find. Please do check your Calcium, alkalinity, and Magnesium to make certain all are in spec before you start. I have also used a marine buffer or a chelated Calcium supplement when I wanted to adjust one or the other. Hope this helps