Hello Stotts...
Don't fret. It's likely a form of algae or something of this kind. Algae grows when there are more nutrients in the water than the plants use. Large weekly water changes will help and you can reduce the amount you feed. Aquarium fish can easily subsist on a couple of small feedings a week. Look for Anacharis plants the next time you're at the pet store. This plant grows floated and will use extra nutrients. It also gives off a mild chemical that will slow the growth of most kinds of algae. I float this plant in my planted tanks and have no algae problems.
B
