Small, thin roots on all my phals... Why??
 

I have three phals and all seem to be doing well and all three are in the process of growing a new leaf. For simplicity, I will call them phal 1, phal 2, and phal 3.
Phal 1 and 2 have a large healthy root system and I have recently observed that they are both pushing out a root. Phal 1's root grew half a centimeter and stopped and barely even has a green tip on it now... It also came out way thinner than it's other roots. Phal 2 is pushing out a root but also much thinner than it's other roots... I have observed other phals pushing out roots (my mom has a big collection) and the roots came out even fatter than older ones... I have never read anything about this problem before so I don't know what's going on.
Phal 3 was my first orchid, and it's been a year since I started this wonderful hobby. This poor thing suffered from root rot in the beginning of my owning it. Since recovering, it has grown 4 new roots (making it a total of 5 roots) and 3 new leaves (making it a total of 4). But even though its leaves seem to be growing well, it has not grown any new roots for approximately 5-6 months! One of it's leaves did burn a little recently after which I started making sure that it got no more direct sunlight. I don't think that would cause the problem of no new roots though....
All these orchids receive pretty good light, and it doesn't drop lower that 70 degrees inside the appartment. I fertilize them every other watering. My other orchids (oncidiums and a beallara) have great new roots all the time. What's going on with my phals? Please help!

Not sure :hmm

I usually find roots come out about the same thickness as old ones and I'm not sure what might influence them to be thinner.

The only thing I've noticed is that the Phals I've converted to S/H are growing big fat thick roots, much bigger than their old ones. This makes me wonder whether yours are on the dry side... if lots of water makes them fatter does too little make them thinner... but I really am just guessing :scratchhead: