Planted Tank Guru
Join Date: Dec 2009
Location: Salt Lake City, UT
Pogostemon Helferi melted for me when hardness was low, less than 2<dgh, however most of my other plants loved the low hardness. if you really want Pogostemon Helferi to do any better i would aim for 3-5dgh.
far as Ca Mg ratio goes, i would aim for 3:1 or 4:1, most people keep Ca around 30ppm and Mg around 6-8ppm