Mark, I think you are correct in that Reef Advantage will maintain proper magnesium levels. If thats what you're using for calcium. I have not measured it when using it, but know someone that has.
To be honest I would not measure or worry about magnesium or strontium if I used it on a regular basis to maintain calcium along with water changes. Same goes if running a reactor with good media.
I would be wary of magnesium levels when using only kalk to maintain calcium levels.
Its also good to be cautious in the use of trace element additives in newer tanks. They can make algae go wild. Hmm, seems strange they do that when they are all water.
