Pam, I use just the fine fir bark & big perlite.I don't use sphagnum as I can be a heavy waterer so it's too wet for me.That & growing in a greenhouse is the only thing that I do.
Oh geez, they get good light but as to foot candles etc I haven't a clue .They face south at the cool end which doesn't get sun until a little later each day as the house shadow is on greenhouse.In summer they are outdoors in dappled light-more as a 'holding ' situation as the greenhouse gets too hot.