fwiw, i run a calcium reactor and kalk reactor everyday, all day in my sps system which is ~ 400 gallaons. I maintain huge growth rates and my calcium sits at 500 ppm + and dKH is between 14-16. I know thats high, trust me I know, I'm the one that cleans and replaces the impeller sets on every pump twice a month. BUt some thing to think about, even at maintaining levels that high my cost is very low, initial cost was low as well because I built the CA reactor from a prefab canister. So for the average hobbyist, who would maintain 400-450 ca and 9-12 dkh, the cost would be substantially lower than mine, which is already very low. I have a five gallon bucket of kalk from BRS that is still 9/10's full and ive refreshed two kalk reactors about six times each on this one bucket. for the calcium reactor i use a mix of Bwel's Neo Mag, Aqua medic's hydro carbonate, and carib sea coarse ARM. Ive tested potassium, strontium, calcium, magnesium, and alkalinity. Between the two systems, my average cost per two months ( i only added calcium reactor medium 6-7 times per year) is around 25-30 bucks. Now that's on a 400 gallon sytem packed with sps. If I take the systems off line i drop about 100-150 mg/l of calcium every 24-48 hours and my alk drops rapidly. I guess for me, if I could afford to dose B-ionic and not have to raise my prices I would because ive seen alot of before and after pics and it is a solid product. It grows softs as well because of the iodide in the formula. The mix of calcium reactor media that I use gives all of the major and some of the minor elements, i dose a supplement for all of the trace.
Just thought id chime in
Sean