Need some help. Plants dying...I think.

[MarcoS]

As you can see the swords are kind eaten/transparent and I have no idea what is causing this. Any thoughts? 

[lefty o]

are you fertilizing at all?

[Theplatymaster]

i agree with @lefty o it could be a nutrient deficiency,

on a side note, i like the LEGO.

[FLFishChik]

This looks like a nutrient deficiency. Swords are very, very  heavy root feeders. I have one in my 29g that I surround with 4-5 root tabs every month.  
  Try trimming off the dying leaves close to the bottom of the stem, give it some root tabs and dose your water column with a liquid fertilizer regularly according your nitrate levels and watch to see if the new growth looks normal as it should.

[knee]

You need to fertilize the tank. Liquid fert and root tabs are recommended but if you can't get any root tabs, liquid ferts will do. Amazon swords also absorb through their leaves but feed heavier on the roots. 

 

[Shaeff]

Hello MarcoS, 

Amazon swords mainly feed from their roots so root tabs will be best for fertilization over liquid for the water column. It does look like it could be a combination of deficiencies so I included 2 images that helped me. To verify which one you can buy additional test beyond the standard strip/API master  (potassium, phosphate etc). When making a correction / adjustment remember to take some time and small adjustments to not over correct or too fast causing a greater issue, best luck.

[ccc24]

I would agree - what is your fertilizer schedule/types? That will help pinpoint your issue.