How to stop plants from turning pale?

I have a 5 gallon tank with four Pseudomugil gertrudae, two algae-eating shrimp, and a few Malaysian trumpet snails and a multitude of plants. The crypts (2), Java fern (3), Java moss, and watersprite are doing well, but the two microswords I bought are turning increasingly pale. I have two fluorescent lights on the tank, a 15W plant light and a 15W full spectrum, use Black Onyx sand for a substrate (made for plants) and add just a little Kent Botanica "Grow" once a week. What can I do to get the microswords back to the dark green they were when I bought them?