These mushrooms are very hardy. I only have a 30 x 2 flourescent light on my tank and have several mushrooms. They don't like strong current but don't really mind either. My mushrooms have grown and expanded under these conditions already.
I would suggest purchasing a invertabrate kit from ***** (cost $15) that comes with calcium, iodine and strontium & molybdenum. Just pour a teaspoon of each into the tank each week to keep the shrooms healthy.
Obviously good water conditions and regular maintenance, but other than that, they're easier to keep than clowns.