Need Rotala macaranda help

About four weeks ago, I set up my 40-gallon plant tank and everything in it
has grown very well except for a bunch of Rotala macaranda. The Rotala has
not taken root and although some stems are throwing out new branches,
almost every stem is decomposing from the ground up. This was not a very
healthy bunch to start with but I wonder what to do now. Should I try
topping them off and planting the still healthy portions? Thanks in

When I planted them, I stripped off two sets of leaves and stuck the bare
stems in the substrate with tweezers. I am using a sand substrate (1-2mm
grains) 1-inch thick over a sand/vermiculite mixture (much finer sand, 60
mesh) 1-1/2" thick. There is a 1-1/2" layer of the fine sand and laterite
below this. I added a sprinkling of crushed lily tablet to the middle
layer. Temp is 67F. pH is 6.5 and stable. There is CO2 from DIY yeast
solution. dKh is 5. Oh, yeah, there's lots of light.

Everything else is thriving--anubias nana, liliaeopsis (spreading all
over), sword plant, h. polysperma, h. sunset whatever, lilies, ludwigia
(red), Java ferns, pennywort, ... Roots penetrated to the bottom layer
within a week after planting.

Greg. Tong
San Francisco, CA, USA
gtong at sirius_com

"Every infinity is composed of only two halves."