Planted Tank Guru
Join Date: Dec 2002
Location: Portland Orygun
Take a few minutes and read my Guide.
Then tell us how long the tank has been set up. Also a sugar based CO2 system, while possible on a 55 gallon tank is a LOT of work and will require a mix far larger than what your store bought system has.
It's possible that your sword plants are making the transition from emerged growth to submerged growth.