Eusterallis Stellata

I have some Eusterallis Stellata that is just surviving. The leaves are
light green (which seems to indicate a lack of iron) but there is
something else that bothers me. The leaves grow out and then curl
tightly at the ends. I figure it has to be some sort of deficiency in
the water but I have no idea. Any suggestions?

Justin Healy in cloudy Savannah