hello, Same problem. I have salifert MG powder type (best and fastest) , Kent brand, Seachem etc etc. My MG from 1400 and my CA 200+
when my CA slow reach 400, MG is dropping to 600 PPM . Worst then u.
i ever try 80% water change
I had tried going back to my dad house to collect their tap water. (purely no filter) , now my MG back to 1050 PPM (2 mths) hope still can push up.
How i know?
I had F/W CRS (shrimps) , my water cycle 2 days also will kill my CRS,
my dad place, Don't even think, just 30% water change, CRS still can breeding. By the way, both place is take care by myself.
But i still unhappy with my MG problem....
By the way, my house got filter and unfilter water, both unsuccessful .I not sure is it my location is so important. Just that my dad place also have marine tank, take care by me too, Don't have so many problem. OR maybe feng Shu problem LOL