How big is your tank ,also what are your water conditions like?? It depends on how big your tank is but, you might need to up your wattage. Don't rush out and buy new lights though because it wil depend on your tank size. Too much light will really bleach them out just as much or worse than to little will bleach them.
In addtion to the energy it gets from the light it will eat small bits of meaty foods formula 1, mysis, etc. They won't eber grow as fast as shroom and you might have to frag it. You could also put it in a higher flow area of your tank that may encourage it to move and it will leave bits of it's foot behind they'll grow into new rics. There are several differnt ways to frag these guys to so when you're ready post.
hth
Chris