I have a solitary hygro stricta on a corner of my 17-gallon tank.
I am sure that I have all the requirements for the more demanding
high light plants since their top are turning red and growing thicker
whorls.
But I seem to have problems with the Hygro Stricta and Corymbosa
"Compact" species.

After 2 weeks or so, I started to see sections
of Stricta's leaves missing, like as if there are plant-eating snails
in the tank (which there are not!). Sometimes the whole tip of
the plant just broke off and float to the surface. They are also
being attacked by spot algae. I notice that the Stricta
and Corymbosa leaves are turning light green. Each day passing,
it seems that it will grow almost yellowish.

Now, all this is a bit strange since I dose the tank 3 times
a week with Flourish Potassium, Flourish Trace Elements and
Dennerle Iron tablets. Lighting is at 4.8 watt/gallon. I know
local water is a bit soft (2 GH) so I sometimes add CaCO3
vitamins...

Any advice or info will be appreciated.