Do you do regular water changes? Should do at least 25% a week. I do 50% a week or a little more.
API liquid regeant test kit. Aquarium pharmaceuticals I think. It has tests for nitrates, nitrites, phopshates, ammonia and others depending on which kit. Any test kit will work just make sure that you get a liquid regeant test kit, more accurate and cheaper in the long run.
It is very important to test for nitrates and phosphates for plants.
The extra lighting will help then.
The calculator makes it really simple to dose what is needed. I would dose potassium, magnesium and calcium regardless because it would be almost impossible to overdose them using the recommended dosing from the calculator.
I am having troubles with any outside messenger or live anything right now. My internet company hates me, I swear. When I have MSN running again I will let you know. Until then, keep asking questions here. Can never ask too many questions, I know I have asked more than my share over the years.