Herf,
You cannot go too far wrong with a balanced fertilizer made for orchids and use it at diluted strength for your phals.
When I had a greenhouse of phals, I used a balanced fertilizer made by Grow More, diluted 1/4 strength and applied every three weeks with the fourth week a flush. I tend to avoid the expensive potions and found Dyna Gro no better than what I was using. There are many brands out there, some with urea and some without; some with more trace elements than others but all of them will work better than nothing.
I do not know in which area of the US you live; where you grow your plants; how much light they get; or what mix they are in. These factors will all affect the absorbing capabilities of the fertilizer you choose.
I hope this helps generally but I know there are several phal growers out there with more specific information.
Good Luck,
CL