Actually, trreherd, you provided your own answer in one of your posts. When stating that the anacharis that is receiving direct sunlight is doing well. The problem isn't wpg related, as anacharis can thrive in 1wpg, (I've done this), it's more a spectrum of lighting that is lacking for the plants not receiving direct sunlight. Fertilizers may also help, but the primary problem you are describing is the lack of spectrum. If you focus on bulbs designed for plants, covering full spectrum, up to 8000K per bulb, you should be just fine without having to do the work of running CO2.
I raise anacharis in my goldfish tank, and it grows faster than they can eat it, which is quite a bit. I use NutriGrow (from Coralife) and FloraSun (by ZooMed) for bulbs on that tank, no fertilizers, no CO2, nothing special other than the full spectrum bulbs.
The lights are on a timer set to run 10 hrs/day, but I would not exceed 12 hrs in a day. Plants also need dark to be healthy. When the lights are on they soak up carbon dioxide and give off oxygen. When the lights are off, the process reverses, and they need both phases in order to thrive and stay healthy.