More light. The light you are running is adequate to sustain a plant of maybe one foot tall. That plant in the 3 gallon looks to be much more than that. Only the two top leaves are getting usable light, so the bottom is giving up on ya.

Do you have hydrocorals mixed in your soil as well? Also, get some kind of air circulation for them. Even if it's a dollar store fan, they need something to replace the air.

More light. I just wanted to make sure I said that again. More light, then work on the rest or it will all be in vein anyways.