Root Rot in Phalaenopsis Needed repotting

[CR7cristiano]

I have a Phal that i discovered to have root rot after i noticed it was very loose in its pot even though it was packed rather tightly.
Bare in mind that i got this orchid in December 2011 and it had Bloomed three times since up until almost a month now when i cut the spike.

The real question i have is afte removing the plant from the pot and cutting away all the dead roots i have maybe 3 healthy plump roots remaining. I soaked the roots in a fungicide/bactericide solution for a day. How long should i now soak it in a mix of fertilizer and superthrive before repotting in a gravel mix?

thanks