Definitely keep some of the anubias roots out of the substrate. They will often die if you don't. I personally disagree with the "too much light" suggestion. 10W over a 20 long is not very strong at all. In fact, it's very weak. Your spectrum seems like it grows algae well. What brand is the light? I also believe that your light needs to be stronger because your plants are covered with algae, which tells me that a lot of the light they need is being blocked. You should clean the leaves or get an algae eater that will do so. What is your temperature? pH? Do you dose with aquarium fertilizers? Yellow leaves are a common symptom of an iron deficiency. Pale green leaves can often be fixed with fertilizers as well. Sometimes even epsom salt (found in nearly all of the ferilizer products) can alleviate this.