The internet says pygmy chain sword need lots of light and ferts...
I do not accept this, especially the light. Admittedly, it depends upon what one means by "low", "moderate" or "high" light, terms which as I have previously written I do not like using because they are subjective and very inconsistent.
Many believe I have low light, with less than one watt of full spectrum per gallon in my 115g tank. Yet this plant absolutely runs rampant, I am pulling up runners regularly; same in my 90g [check my Aquariums photos to see this]. Some sites will say it can't be grown with less than 2-3 watts per gallon. Obviously not accurate.
Swords need nutrients, so do all plants if they are to grow healthy and lush. Larger swords benefit from substrate tabs/sticks, but not the pygmy chain swords.