I was at a discount store and they had Miracle grow fertilizer sticks for $2. I bought it to try. 6-12-6 ratio. With a trace of boron 0.02 and copper 0.05. I doubt enough to harm anything. 30 sticks and I can tell half a stick would be enough for an aquarium plant.
I'm actually cutting down the light to the tank..longer days mean I don't even need the LED..just a pair of fluorescents to bring out the color of everything. LED will return in winter.