I do not understand why my amazon sword is looking so bad, I give it seachem root abs every month and the lighting has always been ok for but recently this month it has started to look like this. I have done changed anything or added anything.
I'm not positive this is what's happening to you but I'll just share my personal experience.
My amazon sword's leaves will die but it's always growing new ones all the time. I usually just pick off the dead leaves and they regrow. Does it look like there's any smaller new leaves growing? How long has it been like this?
Also when I first got my amazon sword I put API Leaf Zone. That might help.
Yeah, I was looking for root tabs and I was only able to find Seachem and API ones, I havent red on API ones but Seachem only seem to be the root tab version of their Flourish liquid fert which only has micros.
I only use potassium sulfate and Seachem Fluorish in my tanks and my plants seem to do well, so yeah, maybe the OP should try complementing with potassium sulfate or KNO3 and see how it goes.