I'm afraid that is probably just an algae growth that seems to colonize dead sphagnum and make it look dark green. It fools us all at one point until we see real, live sphagnum. Here are some pics though, to judge for yourself. First I'll post a couple shots of the dead, "algae" sphagnum. (Check out my Vanzo wondering what the heck I'm doing in there!)I have some filling some cracks at the top of the viv and it is a lush dark green.
Here are a couple shots of live sphagnum. It is growing directly under two T12 bulbs in a cheap, Lowe's shop light. It is about 8 inches under the bulbs. (about 20 cm) This is NOT enough light. When the bulbs were new, the sphagnum was growing better throughout the upper parts of the viv. as the bulbs have aged just a little, maybe 6 months, most of it has died back. This tells me that before, it was barely enough to support the growth. Two T 5's with excellent reflectors, would probably bring it back.I have some filling some cracks at the top of the viv and it is a lush dark green.