If they're terribly dark green they're getting too much light. A good way to tell if the plant is getting enough or too much light is to judge by leaf color. The leaves should be similar to the color of grass. Be careful however, because
too much light can burn the leaves. Phalaenopsis orchids do not like direct sunlight. I've found filtered light is good for mine. I have two that sit on either side of my piano and the light in the room is filtered by sheer curtains. Thus far, both have responded well to the lighting conditions