I have java ferns and anubias nana in my 55g aquarium, a few months ago my plants were flourishing, they were healthy looking and were growing fast, but as of lately (2-3 months ago) they look unhealthy (brownish and black dots and patches) and their growth has slowed to a standstill. I would like to know what i can do to stimulate plant growth, health, and restore my plants to their former glory. Thanks