I have read in recent posts about the lack of calcium.  I wonder if that's
what my plants are suffering from.  Basically, I have been busy and have not
been changing water and fertilizing as frequently for a couple of months.
My plants have suffered some, but most noticeably a large Amazonicus.  The
new leaves are all deformed, wrinkled, hardened and has dark spots.  I
wonder if this indicates a lack of calcium, or some other nutrient.  I have
resumed water changing and fertilizing, but have not seen any improvements.
My tap water is fairly hard (18 GH, 8.4 KH), so would changing water alone
supply enough calcium to the plants (the water report indicates 84.4 mg/L of
calcium), or should I start adding that oyster shell?