There is no problem in your measuring or the Mg products, the "problem" is elsewhere, something is consuming the Mg. We have found many people with these same problems and it seems to be always the same age tanks 1-2 year old. There is something that consumes that Mg and will last some time, but after that, the consumption turn to normal. The thing is that we would like to know why is that? also, we think that more people have this same problem ( they just don`t know it ) but unfortunately, not many hobbyists measure the Mg consumption.
If someone know the reason for this happening we would like to know also, and learn something new
If someone know the reason for this happening we would like to know also, and learn something new