Help sickly Sword

I've got a Rose Sword that's a little under the weather. The leaves are all
turning yellow/transparent. I've had it about two months so I don't think
it's the submerged leaf syndrome. I did let the floating plants get a little
out of hand, so it might have been a little light deprived, but it's relly
taken a nose drive the last week. I cleaned out some of the floating plants
yesterday to give it some more light, but tonight I found two healthy leaves
floating in the tank. They were discoloured where they had broken off.

My tank conditions are as follows:

Iron .25 (a little high)
Nitrates (10)
PH 7.2
Light 4 wpg
55 tall tank
CO2
Flourite and aquatic soil


TIA